diapedesis: passage of blood cells (especially white blood cells) through intact capillary walls and into the surrounding tissue


dichroism: pleochroism of a crystal so that it exhibits two different colors when viewed from two different directions


diffraction: when light passes sharp edges or goes through narrow slits the rays are deflected and produce fringes of light and dark bands


direct current: an electric current that flows in one direction steadily


DC: an electric current that flows in one direction steadily


direct electric current: an electric current that flows in one direction steadily


signal: an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes


interrupt: a signal that temporarily stops the execution of a program so that another procedure can be carried out


doldrums: a belt of calms and light winds between the northern and southern trade winds of the Atlantic and Pacific


drift: a force that moves something along


impetus: a force that moves something along


impulsion: a force that moves something along


dust devil: a miniature whirlwind strong enough to whip dust and leaves and litter into the air


dust storm: a windstorm that lifts up clouds of dust or sand


duster: a windstorm that lifts up clouds of dust or sand


sandstorm: a windstorm that lifts up clouds of dust or sand


sirocco: a windstorm that lifts up clouds of dust or sand


east wind: a wind from the east


easter: a wind from the east


easterly: a wind from the east


northwest wind: a wind from the northwest


northwester: a wind from the northwest


southwester: a strong wind from the southwest


sou'wester: a strong wind from the southwest


southeaster: a strong wind from the southeast


sou'easter: a strong wind from the southeast


elastic energy: potential energy that is stored when a body is deformed (as in a coiled spring)


elastic potential energy: potential energy that is stored when a body is deformed (as in a coiled spring)


electrical phenomenon: a physical phenomenon involving electricity


electrical power: the product of voltage and current


electric power: the product of voltage and current


wattage: the product of voltage and current


load: the power output of a generator or power plant


electric field: a field of force surrounding a charged particle


dielectric heating: heating of an insulator by a high-frequency electric field


electricity: a physical phenomenon associated with stationary or moving electrons and protons


galvanism: electricity produced by chemical action


electricity: energy made available by the flow of electric charge through a conductor


electrical energy: energy made available by the flow of electric charge through a conductor


electromagnetic radiation: radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge


electromagnetic wave: radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge


nonparticulate radiation: radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge


Hertzian wave: an electromagnetic wave generated by oscillations in an electric circuit


electromagnetic spectrum: the entire frequency range of electromagnetic waves


emission spectrum: spectrum of electromagnetic radiation emitted by a self-luminous source


energy: any source of usable power


energy: (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs


free energy: (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs


energy level: a definite stable energy that a physical system can have; used especially of the state of electrons in atoms or molecules


energy state: a definite stable energy that a physical system can have; used especially of the state of electrons in atoms or molecules


power: (physics) the rate of doing work; measured in watts (= joules/second)


rest energy: the energy equivalent to the mass of a particle at rest in an inertial frame of reference; equal to the rest mass times the square of the speed of light


work: (physics) a manifestation of energy; the transfer of energy from one physical system to another expressed as the product of a force and the distance through which it moves a body in the direction of that force


epiphenomenon: a secondary phenomenon that is a by-product of another phenomenon


event: a phenomenon located at a single point in space-time; the fundamental observational entity in relativity theory


facilitation: (neurophysiology) phenomenon that occurs when two or more neural impulses that alone are not enough to trigger a response in a neuron combine to trigger an action potential


flare: am unwanted reflection in an optical system (or the fogging of an image that is caused by such a reflection)


flashover: an unintended electric discharge (as over or around an insulator)


flood: the rising of a body of water and its overflowing onto normally dry land


inundation: the rising of a body of water and its overflowing onto normally dry land


deluge: the rising of a body of water and its overflowing onto normally dry land


alluvion: the rising of a body of water and its overflowing onto normally dry land


debacle: flooding caused by a tumultuous breakup of ice in a river during the spring or summer


flash flood: a sudden local flood of great volume and short duration


flashflood: a sudden local flood of great volume and short duration


floodhead: a wall of water rushing ahead of the flood


Noah's flood: (Biblical) the great deluge that is said in the Book of Genesis to have occurred in the time of Noah; it was brought by God upon the earth because of the wickedness of human beings


Noachian deluge: (Biblical) the great deluge that is said in the Book of Genesis to have occurred in the time of Noah; it was brought by God upon the earth because of the wickedness of human beings


Noah and the Flood: (Biblical) the great deluge that is said in the Book of Genesis to have occurred in the time of Noah; it was brought by God upon the earth because of the wickedness of human beings


the Flood: (Biblical) the great deluge that is said in the Book of Genesis to have occurred in the time of Noah; it was brought by God upon the earth because of the wickedness of human beings


focus: a point of convergence of light (or other radiation) or a point from which it diverges


focal point: a point of convergence of light (or other radiation) or a point from which it diverges


food chain: (ecology) a community of organisms where each member is eaten in turn by another member


food pyramid: (ecology) a hierarchy of food chains with the principal predator at the top; each level preys on the level below


food web: (ecology) a community of organisms where there are several interrelated food chains


food cycle: (ecology) a community of organisms where there are several interrelated food chains


fair weather: moderate weather; suitable for outdoor activities


sunshine: moderate weather; suitable for outdoor activities


temperateness: moderate weather; suitable for outdoor activities


fata morgana: a mirage in the Strait of Messina (attributed to the Arthurian sorcerer Morgan le Fay)


field: the space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it


field of force: the space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it


force field: the space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it


line of force: an imaginary line in a field of force; direction of the line at any point is the direction of the force at that point


field line: an imaginary line in a field of force; direction of the line at any point is the direction of the force at that point


electrical line of force: a line of force in an electrical field


magnetic line of force: a line of force in a magnetic field


fine spray: precipitation in very small drops


fine structure: the presence of groups of closely spaced spectrum lines observed in the atomic spectrum of certain elements


firelight: the light of a fire (especially in a fireplace)


firestorm: a storm in which violent winds are drawn into the column of hot air rising over a severely bombed area


fluorescence: light emitted during absorption of radiation of some other (invisible) wavelength


fog: droplets of water vapor suspended in the air near the ground


fogbank: a large mass of fog on the sea (as seen from a distance)


force: (physics) the influence that produces a change in a physical quantity


forked lightning: a form of lightning that moves rapidly in a zigzag path with one end divided (fork-like)


chain lightning: a form of lightning that moves rapidly in a zigzag path with one end divided (fork-like)


friar's lantern: a pale light sometimes seen at night over marshy ground


ignis fatuus: a pale light sometimes seen at night over marshy ground


jack-o'-lantern: a pale light sometimes seen at night over marshy ground


will-o'-the-wisp: a pale light sometimes seen at night over marshy ground


friction: the resistance encountered when one body is moved in contact with another


rubbing: the resistance encountered when one body is moved in contact with another


fringe: one of the light or dark bands produced by the interference and diffraction of light


interference fringe: one of the light or dark bands produced by the interference and diffraction of light


gene expression: conversion of the information encoded in a gene first into messenger RNA and then to a protein


grinding: the wearing down of rock particles by friction due to water or wind or ice


abrasion: the wearing down of rock particles by friction due to water or wind or ice


attrition: the wearing down of rock particles by friction due to water or wind or ice


detrition: the wearing down of rock particles by friction due to water or wind or ice


grip: the friction between a body and the surface on which it moves (as between an automobile tire and the road)


traction: the friction between a body and the surface on which it moves (as between an automobile tire and the road)


adhesive friction: the friction between a body and the surface on which it moves (as between an automobile tire and the road)


front: (meteorology) the atmospheric phenomenon created at the boundary between two different air masses


warm front: the front of an advancing mass of warmer air


cold front: the front of an advancing mass of colder air


polar front: the front of an advancing mass of colder air


squall line: a cold front along which squalls or thunderstorms are likely


occluded front: (meteorology) a composite front when colder air surrounds a mass of warm air and forces it aloft


occlusion: (meteorology) a composite front when colder air surrounds a mass of warm air and forces it aloft


greenhouse effect: warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth


greenhouse warming: warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth


inversion: the layer of air near the earth is cooler than an overlying layer


frost heave: upthrust of ground or pavement caused by the freezing of moist soil


frost heaving: upthrust of ground or pavement caused by the freezing of moist soil


gale: a strong wind moving 45-90 knots; force 7 to 10 on Beaufort scale


moderate gale: wind moving 32-38 knots; 7 on the Beaufort scale


near gale: wind moving 32-38 knots; 7 on the Beaufort scale


fresh gale: wind moving 39-46 knots; 8 on the Beaufort scale


strong gale: wind moving 47-54 knots; 9 on the Beaufort scale


whole gale: wind moving 55-63 knots; 10 on the Beaufort scale


storm: a violent weather condition with winds 64-72 knots (11 on the Beaufort scale) and precipitation and thunder and lightning


violent storm: a violent weather condition with winds 64-72 knots (11 on the Beaufort scale) and precipitation and thunder and lightning


northeaster: a storm blowing from the northeast


noreaster: a storm blowing from the northeast


gamma radiation: electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength


gamma ray: electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength


gaslight: light yielded by the combustion of illuminating gas


radiance: the amount of electromagnetic radiation leaving or arriving at a point on a surface


glow: the amount of electromagnetic radiation leaving or arriving at a point on a surface


glowing: the amount of electromagnetic radiation leaving or arriving at a point on a surface


glow: a steady even light without flames


sky glow: illumination of the night sky in urban areas


good luck: a stroke of luck


fluke: a stroke of luck


good fortune: a stroke of luck


serendipity: good luck in making unexpected and fortunate discoveries


gravitational field: a field of force surrounding a body of finite mass


gravity: (physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; ; ; --Albert Einstein


gravitation: (physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; ; ; --Albert Einstein


gravitational attraction: (physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; ; ; --Albert Einstein


gravitational force: (physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; ; ; --Albert Einstein


solar gravity: the gravity of the sun


gun smoke: smoke created by the firing of guns


gust: a strong current of air


blast: a strong current of air


blow: a strong current of air


bluster: a violent gusty wind


sandblast: a blast of wind laden with sand


hail: precipitation of ice pellets when there are strong rising air currents


hailstorm: a storm during which hail falls


half-light: a greyish light (as at dawn or dusk or in dim interiors)


haze: atmospheric moisture or dust or smoke that causes reduced visibility


heat: a form of energy that is transferred by a difference in temperature


heat energy: a form of energy that is transferred by a difference in temperature


geothermal energy: energy derived from the heat in the interior of the earth


histocompatibility: condition in which the cells of one tissue can survive in the presence of cells of another tissue


hot weather: a period of unusually high temperatures


scorcher: an extremely hot day


sultriness: oppressively hot and humid weather


hurricane: a severe tropical cyclone usually with heavy rains and winds moving a 73-136 knots (12 on the Beaufort scale)


hydroelectricity: electricity produced by water power


hysteresis: the lagging of an effect behind its cause; especially the phenomenon in which the magnetic induction of a ferromagnetic material lags behind the changing magnetic field


ice fog: a dense winter fog containing ice particles


pogonip: a dense winter fog containing ice particles


ice storm: a storm with freezing rain that leaves everything glazed with ice


silver storm: a storm with freezing rain that leaves everything glazed with ice


incandescence: the phenomenon of light emission by a body as its temperature is raised


glow: the phenomenon of light emission by a body as its temperature is raised


incidence: the striking of a light beam on a surface


induction: an electrical phenomenon whereby an electromotive force (EMF) is generated in a closed circuit by a change in the flow of current


inductance: an electrical phenomenon whereby an electromotive force (EMF) is generated in a closed circuit by a change in the flow of current


mutual induction: generation of electromotive forces in each other by two adjacent circuits


self-induction: generation of an electromotive force (EMF) in a circuit by changing the current in that circuit; usually measured in henries


inertia: (physics) the tendency of a body to maintain its state of rest or uniform motion unless acted upon by an external force


moment of inertia: the tendency of a body to resist angular acceleration


angular acceleration: (physics) the rate of change of the angular velocity of a rotating body


angular velocity: (physics) the rate of change of the angular position of a rotating body; usually expressed in radians per second or radians per minute


infrared: electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves


infrared light: electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves


infrared radiation: electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves


infrared emission: electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves


infrared spectrum: the spectrum of infrared radiation


interreflection: reciprocal reflection between two reflecting surfaces


jet propulsion: propulsion by means of the discharge of a jet of fluid toward the rear


jet stream: a high-speed high-altitude airstream blowing from west to east near the top of the troposphere; has important effects of the formation of weather fronts


juice: electric current


kinetic energy: the mechanical energy that a body has by virtue of its motion


K.E.: the mechanical energy that a body has by virtue of its motion


heat of dissociation: the heat required for a fluid substance to break up into simpler constituents


heat of formation: the heat evolved or absorbed during the formation of one mole of a substance from its component elements


heat of solution: the heat evolved or absorbed when one mole of a substance is dissolved in a large volume of a solvent


latent heat: heat absorbed or radiated during a change of phase at a constant temperature and pressure


heat of transformation: heat absorbed or radiated during a change of phase at a constant temperature and pressure


heat of condensation: heat liberated by a unit mass of gas at its boiling point as it condenses into a liquid


heat of fusion: heat absorbed by a unit mass of a solid at its melting point in order to convert the solid into a liquid at the same temperature


heat of solidification: heat liberated by a unit mass of liquid at its freezing point when it solidifies


heat of sublimation: heat absorbed by a unit mass of material when it changes from a solid to a gaseous state


heat of vaporization: heat absorbed by a unit mass of a material at its boiling point in order to convert the material into a gas at the same temperature


heat of vaporisation: heat absorbed by a unit mass of a material at its boiling point in order to convert the material into a gas at the same temperature


specific heat: the heat required to raise the temperature of one gram of a substance one degree centigrade


heat ray: a ray that produces a thermal effect


heat wave: a wave of unusually hot weather


high beam: the beam of a car's headlights that provides distant illumination


infrared ray: a ray of infrared radiation; produces a thermal effect (as from an infrared lamp)


lamplight: light from a lamp


levanter: an easterly wind in the western Mediterranean area


leverage: the mechanical advantage gained by being in a position to use a lever


purchase: the mechanical advantage gained by being in a position to use a lever


life: the organic phenomenon that distinguishes living organisms from nonliving ones


biology: characteristic life processes and phenomena of living organisms


aerobiosis: life sustained in the presence of air or oxygen


life cycle: a series of stages through which an organism passes between recurrences of a primary stage


light: (physics) electromagnetic radiation that can produce a visual sensation


visible light: (physics) electromagnetic radiation that can produce a visual sensation


visible radiation: (physics) electromagnetic radiation that can produce a visual sensation


line: a single frequency (or very narrow band) of radiation in a spectrum


elves: an acronym for emissions of light and very low frequency perturbations due to electromagnetic pulse sources; extremely bright extremely short (less than a msec) electrical flashes forming a huge ring (up to 400 km diameter) in the ionosphere


jet: atmospheric discharges (lasting 10 msec) bursting from the tops of giant storm clouds in blue cones that widen as they flash upward


blue jet: atmospheric discharges (lasting 10 msec) bursting from the tops of giant storm clouds in blue cones that widen as they flash upward


reverse lightning: atmospheric discharges (lasting 10 msec) bursting from the tops of giant storm clouds in blue cones that widen as they flash upward


lightning: abrupt electric discharge from cloud to cloud or from cloud to earth accompanied by the emission of light


line spectrum: a spectrum in which energy is concentrated at particular wavelengths; produced by excited atoms and ions as they fall back to a lower energy level


Lorentz force: the force experienced by a point charge moving along a wire that is in a magnetic field; the force is at right angles to both the current and the magnetic field


sprites: atmospheric electricity (lasting 10 msec) appearing as globular flashes of red (pink to blood-red) light rising to heights of 60 miles (sometimes seen together with elves)


red sprites: atmospheric electricity (lasting 10 msec) appearing as globular flashes of red (pink to blood-red) light rising to heights of 60 miles (sometimes seen together with elves)


atmospheric electricity: electrical discharges in the atmosphere


luminescence: light not due to incandescence; occurs at low temperatures


bioluminescence: luminescence produced by physiological processes (as in the firefly)


chemiluminescence: luminescence resulting from a chemical reaction as the oxidation of luciferin in fireflies


luminous energy: the energy associated with visible light


magnetosphere: the magnetic field of a planet; the volume around the planet in which charged particles are subject more to the planet's magnetic field than to the solar magnetic field


solar magnetic field: the magnetic field of the sun


magnetic field: the lines of force surrounding a permanent magnet or a moving charged particle


magnetic flux: the lines of force surrounding a permanent magnet or a moving charged particle


flux: the lines of force surrounding a permanent magnet or a moving charged particle


radiation field: a field that represents the energy lost from the radiator to space


beat: a single pulsation of an oscillation produced by adding two waves of different frequencies; has a frequency equal to the difference between the two oscillations


resonance: a vibration of large amplitude produced by a relatively small vibration near the same frequency of vibration as the natural frequency of the resonating system


sympathetic vibration: (physics) vibration produced by resonance


resonance: an excited state of a stable particle causing a sharp maximum in the probability of absorption of electromagnetic radiation


nuclear resonance: the resonance absorption of a gamma ray by a nucleus identical to the nucleus that emitted the gamma ray


magnetic resonance: resonance of electrons or atoms or molecules or nuclei to radiation frequencies as a result of space quantization in a magnetic field


nuclear magnetic resonance: resonance of protons to radiation in a magnetic field


NMR: resonance of protons to radiation in a magnetic field


proton magnetic resonance: resonance of protons to radiation in a magnetic field


magnetism: attraction for iron; associated with electric currents as well as magnets; characterized by fields of force


magnetic attraction: attraction for iron; associated with electric currents as well as magnets; characterized by fields of force


magnetic force: attraction for iron; associated with electric currents as well as magnets; characterized by fields of force


electromagnetism: magnetism produced by an electric current


antiferromagnetism: magnetic field creates parallel but opposing spins; varies with temperature


diamagnetism: phenomenon exhibited by materials like copper or bismuth that become magnetized in a magnetic field with a polarity opposite to the magnetic force; unlike iron they are slightly repelled by a magnet


ferrimagnetism: a phenomenon in ferrites where there can be incomplete cancellation of antiferromagnetic arranged spins giving a net magnetic moment


ferromagnetism: phenomenon exhibited by materials like iron (nickel or cobalt) that become magnetized in a magnetic field and retain their magnetism when the field is removed


paramagnetism: materials like aluminum or platinum become magnetized in a magnetic field but it disappears when the field is removed


mechanical phenomenon: a physical phenomenon associated with the equilibrium or motion of objects


sound: mechanical vibrations transmitted by an elastic medium


ultrasound: very high frequency sound; used in ultrasonography


trajectory: the path followed by an object moving through space


flight: the path followed by an object moving through space


ballistics: the trajectory of an object in free flight


ballistic trajectory: the trajectory of an object in free flight


gravity-assist: (spaceflight) a trajectory that passes close to a planetary body in order to gain energy from its gravitational field


mass defect: the amount by which the mass of an atomic nucleus is less than the sum of the masses of its constituent particles


mass deficiency: the amount by which the mass of an atomic nucleus is less than the sum of the masses of its constituent particles


mechanical energy: energy in a mechanical form


thaw: warm weather following a freeze; snow and ice melt


thawing: warm weather following a freeze; snow and ice melt


warming: warm weather following a freeze; snow and ice melt


microwave: a short electromagnetic wave (longer than infrared but shorter than radio waves); used for radar and microwave ovens and for transmitting telephone, facsimile, video and data


midnight sun: the sun visible at midnight (inside the Arctic or Antarctic Circles)


mist: a thin fog with condensation near the ground


mistral: a strong north wind that blows in France during the winter


moment: a turning force produced by an object acting at a distance (or a measure of that force)


moment of a couple: given two equal and opposite forces, the product of the force and the distance between them


dipole moment: the moment of a dipole


electric dipole moment: the dipole moment in an electric dipole


magnetic dipole moment: (physics) a current loop gives rise to a magnetic field characteristic of a magnetic dipole


magnetic moment: the torque exerted on a magnet or dipole when it is placed in a magnetic field


moment of a magnet: the torque exerted on a magnet or dipole when it is placed in a magnetic field


meteor: a streak of light in the sky at night that results when a meteoroid hits the earth's atmosphere and air friction causes the meteoroid to melt or vaporize or explode


shooting star: a streak of light in the sky at night that results when a meteoroid hits the earth's atmosphere and air friction causes the meteoroid to melt or vaporize or explode


bolide: an especially luminous meteor (sometimes exploding)


fireball: an especially luminous meteor (sometimes exploding)


mirage: an optical illusion in which atmospheric refraction by a layer of hot air distorts or inverts reflections of distant objects


monsoon: a seasonal wind in southern Asia; blows from the southwest (bringing rain) in summer and from the northeast in winter


monsoon: any wind that changes direction with the seasons


moonbeam: a ray of moonlight


moon ray: a ray of moonlight


moon-ray: a ray of moonlight


moonlight: the light of the Moon


moonshine: the light of the Moon


Moon: the light of the Moon


starlight: the light of the stars


sunburst: a sudden emergence of the sun from behind clouds


sunlight: the rays of the sun


sunshine: the rays of the sun


sun: the rays of the sun


sunbeam: a ray of sunlight


sunray: a ray of sunlight


laser beam: a beam of light generated by a laser


low beam: the beam of a car's headlights that provides illumination for a short distance


particle beam: a collimated flow of particles (atoms or electrons or molecules)


ion beam: a beam of ions moving in the same direction at the same speed


ionic beam: a beam of ions moving in the same direction at the same speed


necrobiosis: (physiology) the normal degeneration and death of living cells (as in various epithelial cells)


cell death: (physiology) the normal degeneration and death of living cells (as in various epithelial cells)


apoptosis: a type of cell death in which the cell uses specialized cellular machinery to kill itself; a cell suicide mechanism that enables metazoans to control cell number and eliminate cells that threaten the animal's survival


programmed cell death: a type of cell death in which the cell uses specialized cellular machinery to kill itself; a cell suicide mechanism that enables metazoans to control cell number and eliminate cells that threaten the animal's survival


caspase-mediated cell death: a type of cell death in which the cell uses specialized cellular machinery to kill itself; a cell suicide mechanism that enables metazoans to control cell number and eliminate cells that threaten the animal's survival


necrosis: the localized death of living cells (as from infection or the interruption of blood supply)


mortification: the localized death of living cells (as from infection or the interruption of blood supply)


gangrene: the localized death of living cells (as from infection or the interruption of blood supply)


sphacelus: the localized death of living cells (as from infection or the interruption of blood supply)


myonecrosis: localized death of muscle cell fibers


brain death: death when respiration and other reflexes are absent; consciousness is gone; organs can be removed for transplantation before the heartbeat stops


cerebral death: death when respiration and other reflexes are absent; consciousness is gone; organs can be removed for transplantation before the heartbeat stops


neutron radiation: radiation of neutrons (as by a neutron bomb)


halo: a circle of light around the sun or moon


solar halo: a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere


parhelic circle: a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere


parhelic ring: a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere


parhelion: a bright spot on the parhelic circle; caused by diffraction by ice crystals


mock sun: a bright spot on the parhelic circle; caused by diffraction by ice crystals


sundog: a bright spot on the parhelic circle; caused by diffraction by ice crystals


north wind: a wind that blows from the north


northerly: a wind that blows from the north


norther: a wind that blows from the north


boreas: a wind that blows from the north


nuclear propulsion: the use of a nuclear reactor either to produce electricity to power an engine (as in a nuclear submarine) or to directly heat a propellant (as in nuclear rockets)


ocean current: the steady flow of surface ocean water in a prevailing direction


El Nino: (oceanography) a warm ocean current that flows along the equator from the date line and south off the coast of Ecuador at Christmas time


El Nino southern oscillation: a more intense El Nino that occurs every few years when the welling up of cold nutrient-rich water does not occur; kills plankton and fish and affects weather patterns


equatorial current: any of the ocean currents that flow westward at the equator


North Equatorial Current: an equatorial current that flows west across the Pacific just north of the equator


South Equatorial Current: an equatorial current that flows west across the Pacific just south of the equator


Gulf stream: a warm ocean current that flows from the Gulf of Mexico northward through the Atlantic Ocean


Japan current: a warm ocean current that flows northeastwardly off the coast of Japan into the northern Pacific ocean


Kuroshio current: a warm ocean current that flows northeastwardly off the coast of Japan into the northern Pacific ocean


Kuroshio: a warm ocean current that flows northeastwardly off the coast of Japan into the northern Pacific ocean


Peruvian current: a cold ocean current that flows north along the Pacific Coast of South America before turning west


Humboldt current: a cold ocean current that flows north along the Pacific Coast of South America before turning west


opacity: the phenomenon of not permitting the passage of electromagnetic radiation


optical opacity: opacity to light


radiopacity: opacity to X-rays or other radiation


radio-opacity: opacity to X-rays or other radiation


optical illusion: an optical phenomenon that results in a false or deceptive visual impression


optical phenomenon: a physical phenomenon related to or involving light


pea soup: a heavy thick yellow fog


pea-souper: a heavy thick yellow fog


phosphorescence: a fluorescence that persists after the bombarding radiation has ceased


photoelectricity: electricity generated by light or affected by light


piezoelectricity: electricity produced by mechanical pressure on certain crystals (notably quartz or Rochelle salt); alternatively, electrostatic stress produces a change in the linear dimensions of the crystal


piezoelectric effect: electricity produced by mechanical pressure on certain crystals (notably quartz or Rochelle salt); alternatively, electrostatic stress produces a change in the linear dimensions of the crystal


piezo effect: electricity produced by mechanical pressure on certain crystals (notably quartz or Rochelle salt); alternatively, electrostatic stress produces a change in the linear dimensions of the crystal


pleochroism: the phenomenon of different colors appearing when certain crystals are viewed from different directions


pleomorphism: (biology) the appearance of two or more distinctly different forms in the life cycle of some organisms


polarization: the phenomenon in which waves of light or other radiation are restricted in direction of vibration


polarisation: the phenomenon in which waves of light or other radiation are restricted in direction of vibration


depolarization: a loss of polarity or polarization


depolarisation: a loss of polarity or polarization


polymorphism: (biology) the existence of two or more forms of individuals within the same animal species (independent of sex differences)


dimorphism: (biology) the existence of two forms of individual within the same animal species (independent of sex differences)


polymorphism: (chemistry) the existence of different kinds of crystal of the same chemical compound


pleomorphism: (chemistry) the existence of different kinds of crystal of the same chemical compound


dimorphism: (chemistry) the property of certain substances that enables them to exist in two distinct crystalline forms


polymorphism: (genetics) the genetic variation within a population that natural selection can operate on


single nucleotide polymorphism: (genetics) genetic variation in a DNA sequence that occurs when a single nucleotide in a genome is altered; SNPs are usually considered to be point mutations that have been evolutionarily successful enough to recur in a significant proportion of the population of a species


SNP: (genetics) genetic variation in a DNA sequence that occurs when a single nucleotide in a genome is altered; SNPs are usually considered to be point mutations that have been evolutionarily successful enough to recur in a significant proportion of the population of a species


electric potential: the difference in electrical charge between two points in a circuit expressed in volts


potential: the difference in electrical charge between two points in a circuit expressed in volts


potential difference: the difference in electrical charge between two points in a circuit expressed in volts


potential drop: the difference in electrical charge between two points in a circuit expressed in volts


voltage: the difference in electrical charge between two points in a circuit expressed in volts


evoked potential: the electrical response of the central nervous system produced by an external stimulus


resting potential: the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse


potential energy: the mechanical energy that a body has by virtue of its position; stored energy


P.E.: the mechanical energy that a body has by virtue of its position; stored energy


precipitation: the falling to earth of any form of water (rain or snow or hail or sleet or mist)


downfall: the falling to earth of any form of water (rain or snow or hail or sleet or mist)


gas pressure: the pressure exerted by a gas


pressure: the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)


pressure level: the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)


force per unit area: the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)


head: the pressure exerted by a fluid


barometric pressure: atmospheric pressure as indicated by a barometer


compartment pressure: the air pressure maintained in an air-tight compartment (as in an aircraft)


overpressure: a transient air pressure greater than the surrounding atmospheric pressure


sea-level pressure: the atmospheric pressure reduced by a formula to the pressure at sea level


hydrostatic head: the pressure at a given point in a liquid measured in terms of the vertical height of a column of the liquid needed to produce the same pressure


intraocular pressure: pressure exerted by the fluids inside the eyeball; regulated by resistance to the outward flow of aqueous humor


IOP: pressure exerted by the fluids inside the eyeball; regulated by resistance to the outward flow of aqueous humor


oil pressure: pressure that keeps oil on the moving parts of an internal-combustion engine


osmotic pressure: (physical chemistry) the pressure exerted by a solution necessary to prevent osmosis into that solution when it is separated from the pure solvent by a semipermeable membrane


radiation pressure: the minute pressure exerted on a surface normal to the direction of propagation of a wave


corpuscular-radiation pressure: the minute pressure exerted on a surface normal to the direction of propagation of a wave


sound pressure: the difference between the instantaneous pressure at a point in a sound field and the average pressure at that point


instantaneous sound pressure: the difference between the instantaneous pressure at a point in a sound field and the average pressure at that point


prevailing wind: the predominant wind direction


propulsion: a propelling force


puff: a short light gust of air


puff of air: a short light gust of air


whiff: a short light gust of air


pull: the force used in pulling


push: the force used in pushing


thrust: the force used in pushing


reaction: (mechanics) the equal and opposite force that is produced when any force is applied to a body


rocket propulsion: reaction propulsion using stored oxygen for combustion; used where there is insufficient atmospheric oxygen


reaction propulsion: propulsion that results from the ejection at high velocity of a mass of gas to which the vehicle reacts with an equal and opposite momentum


radiant energy: energy that is transmitted in the form of (electromagnetic) radiation; energy that exists in the absence of matter


radiation: energy that is radiated or transmitted in the form of rays or waves or particles


corpuscular radiation: a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons)


particulate radiation: a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons)


radio wave: an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m


radio emission: an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m


radio radiation: an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m


sky wave: a radio wave that is reflected back to earth by the ionosphere or a communications satellite; permits transmission around the curve of the earth's surface


ionospheric wave: a sky wave that is reflected by the ionosphere


ground wave: a radio wave propagated on or near the earth's surface


radio signal: a radio wave used to transmit and receive messages


mass spectrum: a distribution of ions as shown by a mass spectrograph or a mass spectrometer


microwave spectrum: the part of the electromagnetic spectrum corresponding to microwaves


radio spectrum: the entire spectrum of electromagnetic frequencies used for communications; includes frequencies used for radio and radar and television


radio-frequency spectrum: the entire spectrum of electromagnetic frequencies used for communications; includes frequencies used for radio and radar and television


carrier wave: a radio wave that can be modulated in order to transmit a signal


carrier: a radio wave that can be modulated in order to transmit a signal


rain: water falling in drops from vapor condensed in the atmosphere


rainfall: water falling in drops from vapor condensed in the atmosphere


raindrop: a drop of rain


rainstorm: a storm with rain


line storm: a violent rainstorm near the time of an equinox


equinoctial storm: a violent rainstorm near the time of an equinox


thundershower: a short rainstorm accompanied by thunder and lightning


downpour: a heavy rain


cloudburst: a heavy rain


deluge: a heavy rain


waterspout: a heavy rain


torrent: a heavy rain


pelter: a heavy rain


soaker: a heavy rain


drizzle: very light rain; stronger than mist but less than a shower


mizzle: very light rain; stronger than mist but less than a shower


shower: a brief period of precipitation


rain shower: a brief period of precipitation


recognition: (biology) the ability of one molecule to attach to another molecule that has a complementary shape


reflection: the phenomenon of a propagating wave (light or sound) being thrown back from a surface


reflexion: the phenomenon of a propagating wave (light or sound) being thrown back from a surface


refraction: the change in direction of a propagating wave (light or sound) when passing from one medium to another


double refraction: splitting a ray into two parallel rays polarized perpendicularly


birefringence: splitting a ray into two parallel rays polarized perpendicularly


resistance: any mechanical force that tends to retard or oppose motion


conductance: a material's capacity to conduct electricity; measured as the reciprocal of electrical resistance


electric resistance: a material's opposition to the flow of electric current; measured in ohms


electrical resistance: a material's opposition to the flow of electric current; measured in ohms


impedance: a material's opposition to the flow of electric current; measured in ohms


resistance: a material's opposition to the flow of electric current; measured in ohms


resistivity: a material's opposition to the flow of electric current; measured in ohms


ohmic resistance: a material's opposition to the flow of electric current; measured in ohms


ohmage: the ohmic resistance of a conductor


reactance: opposition to the flow of electric current resulting from inductance and capacitance (rather than resistance)


acoustic resistance: opposition to the flow of sound through a surface; acoustic resistance is the real component of acoustic impedance and acoustic reactance is the imaginary component


acoustic impedance: opposition to the flow of sound through a surface; acoustic resistance is the real component of acoustic impedance and acoustic reactance is the imaginary component


acoustic reactance: opposition to the flow of sound through a surface; acoustic resistance is the real component of acoustic impedance and acoustic reactance is the imaginary component


reluctance: (physics) opposition to magnetic flux (analogous to electric resistance)


drag: the phenomenon of resistance to motion through a fluid


retarding force: the phenomenon of resistance to motion through a fluid


sonic barrier: the increase in aerodynamic drag as an airplane approaches the speed of sound


sound barrier: the increase in aerodynamic drag as an airplane approaches the speed of sound


windage: the retarding force of air friction on a moving object


rejection: (medicine) an immunological response that refuses to accept substances or organisms that are recognized as foreign


rejuvenation: the phenomenon of vitality and freshness being restored


greening: the phenomenon of vitality and freshness being restored


resolving power: the ability of a microscope or telescope to measure the angular separation of images that are close together


resolution: the ability of a microscope or telescope to measure the angular separation of images that are close together


resolution: (computer science) the number of pixels per square inch on a computer-generated display; the greater the resolution, the better the picture


scattering: a light shower that falls in some locations and not others nearby


sprinkle: a light shower that falls in some locations and not others nearby


sprinkling: a light shower that falls in some locations and not others nearby


scintillation: (physics) a flash of light that is produced in a phosphor when it absorbs a photon or ionizing particle


sex linkage: an association between genes in sex chromosomes that makes some characteristics appear more frequently in one sex than in the other


shear: (physics) a deformation of an object in which parallel planes remain parallel but are shifted in a direction parallel to themselves


meteor shower: a transient shower of meteors when a meteor swarm enters the earth's atmosphere


meteor stream: a transient shower of meteors when a meteor swarm enters the earth's atmosphere


short wave: a radio wave with a wavelength less than 100 meters (a frequency greater than 3 megahertz)


medium wave: a radio wave with a wavelength between 100 and 1000 meters (a frequency between 300 kilohertz and 3000 kilohertz)


long wave: a radio wave with a wavelength longer than a kilometer (a frequency below 300 kilohertz)


simoom: a violent hot sand-laden wind on the deserts of Arabia and North Africa


simoon: a violent hot sand-laden wind on the deserts of Arabia and North Africa


samiel: a violent hot sand-laden wind on the deserts of Arabia and North Africa


skin effect: the tendency of high-frequency alternating current to distribute near the surface of a conductor


sleet: partially melted snow (or a mixture of rain and snow)


smoke: a cloud of fine particles suspended in a gas


fume: a cloud of fine particles suspended in a gas


smother: a stifling cloud of smoke


snow: precipitation falling from clouds in the form of ice crystals


snowfall: precipitation falling from clouds in the form of ice crystals


flurry: a light brief snowfall and gust of wind (or something resembling that)


snow flurry: a light brief snowfall and gust of wind (or something resembling that)


whiteout: an arctic atmospheric condition with clouds over snow produce a uniform whiteness and objects are difficult to see; occurs when the light reflected off the snow equals the light coming through the clouds


snowflake: a crystal of snow


flake: a crystal of snow


virga: light wispy precipitation that evaporates before it reaches the ground (especially when the lower air is low in humidity)


ice crystal: small crystals of ice


snow mist: small crystals of ice


diamond dust: small crystals of ice


poudrin: small crystals of ice


ice needle: small crystals of ice


frost snow: small crystals of ice


frost mist: small crystals of ice


blizzard: a storm with widespread snowfall accompanied by strong winds


snowstorm: a storm with widespread snowfall accompanied by strong winds


solar energy: energy from the sun that is converted into thermal or electrical energy


solar power: energy from the sun that is converted into thermal or electrical energy


insolation: incident solar radiation


solar radiation: radiation from the sun


solar flare: a sudden eruption of intense high-energy radiation from the sun's surface; associated with sunspots and radio interference


flare: a sudden eruption of intense high-energy radiation from the sun's surface; associated with sunspots and radio interference


solar prominence: large eruptions of luminous hydrogen gas that rise thousands of kilometers above the chromosphere


solar wind: a stream of protons moving radially from the sun


sound spectrum: the distribution of energy as a function of frequency for a particular sound source


acoustic spectrum: the distribution of energy as a function of frequency for a particular sound source


speech spectrum: the average sound spectrum for the human voice


sunspot: a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field


macula: a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field


facula: a large bright spot on the sun's photosphere occurring most frequently in the vicinity of sunspots


facula: a bright spot on a planet


south wind: a wind from the south


souther: a wind from the south


southerly: a wind from the south


discharge: electrical conduction through a gas in an applied electric field


spark: electrical conduction through a gas in an applied electric field


arc: electrical conduction through a gas in an applied electric field


electric arc: electrical conduction through a gas in an applied electric field


electric discharge: electrical conduction through a gas in an applied electric field


distortion: a change (usually undesired) in the waveform of an acoustic or analog electrical signal; the difference between two measurements of a signal (as between the input and output signal)


nonlinear distortion: distortion that occurs when the output signal does not have a linear relation to the input signal


amplitude distortion: distortion that occurs when the output signal does not have a linear relation to the input signal


projection: the acoustic phenomenon that gives sound a penetrating quality


acoustic projection: the acoustic phenomenon that gives sound a penetrating quality


sound projection: the acoustic phenomenon that gives sound a penetrating quality


electrical conduction: the passage of electricity through a conductor


conduction: the transmission of heat or electricity or sound


conductivity: the transmission of heat or electricity or sound


propagation: the movement of a wave through a medium


Doppler effect: change in the apparent frequency of a wave as observer and source move toward or away from each other


Doppler shift: change in the apparent frequency of a wave as observer and source move toward or away from each other


red shift: (astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding


redshift: (astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding


wave front: all the points just reached by a wave as it propagates


spherical aberration: an optical aberration resulting in a distorted image


spillover: (economics) any indirect effect of public expenditure


squall: sudden violent winds; often accompanied by precipitation


line squall: a squall advancing along a front that forms a definite line


electrical disturbance: electrical signals produced by unwanted sources (atmospherics or receiver noise or unwanted transmitters)


static electricity: electricity produced by friction


dynamic electricity: a flow of electric charge


current electricity: a flow of electric charge


thermoelectricity: electricity produced by heat (as in a thermocouple)


stress: (physics) force that produces strain on a physical body


tension: (physics) a stress that produces an elongation of an elastic physical body


strain: (physics) deformation of a physical body under the action of applied forces


breaking point: the degree of tension or stress at which something breaks


overstrain: too much strain


streamer: light that streams


torchlight: light from a torch or torches


twilight: the diffused light from the sky when the sun is below the horizon but its rays are refracted by the atmosphere of the earth


interaction: (physics) the transfer of energy between elementary particles or between an elementary particle and a field or between fields; mediated by gauge bosons


fundamental interaction: (physics) the transfer of energy between elementary particles or between an elementary particle and a field or between fields; mediated by gauge bosons


electromagnetic interaction: an interaction between charged elementary particles that is intermediate in strength between the strong and weak interactions; mediated by photons


gravitational interaction: a weak interaction between particles that results from their mass; mediated by gravitons


strong interaction: (physics) the interaction that binds protons and neutrons together in the nuclei of atoms; mediated by gluons


strong force: (physics) the interaction that binds protons and neutrons together in the nuclei of atoms; mediated by gluons


color force: (physics) the interaction that binds protons and neutrons together in the nuclei of atoms; mediated by gluons


supertwister: the most powerful tornado which can create enormously devastating damage


weak interaction: (physics) an interaction between elementary particles involving neutrinos or antineutrinos that is responsible for certain kinds of radioactive decay; mediated by intermediate vector bosons


weak force: (physics) an interaction between elementary particles involving neutrinos or antineutrinos that is responsible for certain kinds of radioactive decay; mediated by intermediate vector bosons


suction: a force over an area produced by a pressure difference


sunrise: atmospheric phenomena accompanying the daily appearance of the sun


sunset: atmospheric phenomena accompanying the daily disappearance of the sun


afterglow: a glow sometimes seen in the sky after sunset


surface tension: a phenomenon at the surface of a liquid caused by intermolecular forces


interfacial tension: surface tension at the surface separating two non-miscible liquids


interfacial surface tension: surface tension at the surface separating two non-miscible liquids


syzygy: the straight line configuration of 3 celestial bodies (as the sun and earth and moon) in a gravitational system


tempest: (literary) a violent wind


thermal: rising current of warm air


thermionic current: an electric current produced between two electrodes as a result of electrons emitted by thermionic emission


theta rhythm: the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude


theta wave: the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude


thunderbolt: a discharge of lightning accompanied by thunder


bolt: a discharge of lightning accompanied by thunder


bolt of lightning: a discharge of lightning accompanied by thunder


thunderstorm: a storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning


electrical storm: a storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning


electric storm: a storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning


tornado: a localized and violently destructive windstorm occurring over land characterized by a funnel-shaped cloud extending toward the ground


twister: a localized and violently destructive windstorm occurring over land characterized by a funnel-shaped cloud extending toward the ground


torsion: a twisting force


torque: a twisting force


tossup: an unpredictable phenomenon


toss-up: an unpredictable phenomenon


even chance: an unpredictable phenomenon


trade wind: steady winds blowing from east to west above and below the equator


trade: steady winds blowing from east to west above and below the equator


antitrade wind: winds blowing from west to east and lying above the trade winds in the tropics


antitrade: winds blowing from west to east and lying above the trade winds in the tropics


tramontane: a cold dry wind that blows south out of the mountains into Italy and the western Mediterranean


tramontana: a cold dry wind that blows south out of the mountains into Italy and the western Mediterranean


transgression: the spreading of the sea over land as evidenced by the deposition of marine strata over terrestrial strata


transparency: permitting the free passage of electromagnetic radiation


transparence: permitting the free passage of electromagnetic radiation


trichroism: pleochroism of a crystal so that it exhibits three different colors when viewed from three different directions


turbulence: unstable flow of a liquid or gas


turbulency: unstable flow of a liquid or gas


typhoon: a tropical cyclone occurring in the western Pacific or Indian oceans


turbulent flow: flow in which the velocity at any point varies erratically


sea: turbulent water with swells of considerable size


head sea: a sea in which the waves are running directly against the course of the ship


streamline flow: flow of a gas or liquid in which the velocity at any point is relatively steady


laminar flow: nonturbulent streamline flow in parallel layers (laminae)


ultraviolet: radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays


ultraviolet radiation: radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays


ultraviolet light: radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays


ultraviolet illumination: radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays


UV: radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays


sunray: a ray of artificial ultraviolet light from a sunray lamp


sun-ray: a ray of artificial ultraviolet light from a sunray lamp


ultraviolet spectrum: the spectrum of ultraviolet radiation


draft: a current of air (usually coming into a chimney or room or vehicle)


draught: a current of air (usually coming into a chimney or room or vehicle)


updraft: a strong upward air current


downdraft: a strong downward air current


van der Waal's forces: relatively weak attraction between neutral atoms and molecules arising from polarization induced in each particle by the presence of other particles


vapor pressure: the pressure exerted by a vapor; often understood to mean saturated vapor pressure (the vapor pressure of a vapor in contact with its liquid form)


vapour pressure: the pressure exerted by a vapor; often understood to mean saturated vapor pressure (the vapor pressure of a vapor in contact with its liquid form)


virtual image: a reflected optical image (as seen in a plane mirror)


visible spectrum: the distribution of colors produced when light is dispersed by a prism


color spectrum: the distribution of colors produced when light is dispersed by a prism


voltage: the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts


electromotive force: the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts


emf: the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts


magnetomotive force: the force that produces magnetic flux


life force: (biology) a hypothetical force (not physical or chemical) once thought by Henri Bergson to cause the evolution and development of organisms


vital force: (biology) a hypothetical force (not physical or chemical) once thought by Henri Bergson to cause the evolution and development of organisms


vitality: (biology) a hypothetical force (not physical or chemical) once thought by Henri Bergson to cause the evolution and development of organisms


elan vital: (biology) a hypothetical force (not physical or chemical) once thought by Henri Bergson to cause the evolution and development of organisms


volcanism: the phenomena associated with volcanic activity


waterpower: the power to do work that is latent in a head of water


waterspout: a tornado passing over water and picking up a column of water and mist


wave: a persistent and widespread unusual weather condition (especially of unusual temperatures)


weather: the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation


weather condition: the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation


conditions: the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation


atmospheric condition: the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation


elements: violent or severe weather (viewed as caused by the action of the four elements)


west wind: wind that blows from west to east


wester: wind that blows from west to east


prevailing westerly: the winds from the west that occur in the temperate zones of the Earth


westerly: the winds from the west that occur in the temperate zones of the Earth


whirlwind: a more or less vertical column of air whirling around itself as it moves over the surface of the Earth


wind: air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure


air current: air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure


current of air: air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure


wind generation: power derived from the wind (as by windmills)


wind power: power derived from the wind (as by windmills)


windstorm: a storm consisting of violent winds


X ray: electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target


X-ray: electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target


X-radiation: electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target


roentgen ray: electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target


X-ray diffraction: the scattering of X rays by the atoms of a crystal; the diffraction pattern shows structure of the crystal


zodiacal light: a luminous tract in the sky; a reflection of sunlight from cosmic dust in the plane of the ecliptic; visible just before sunrise and just after sunset


chop: the irregular motion of waves (usually caused by wind blowing in a direction opposite to the tide)


flotation: the phenomenon of floating (remaining on the surface of a liquid without sinking)


floatation: the phenomenon of floating (remaining on the surface of a liquid without sinking)


parallax: the apparent displacement of an object as seen from two different points that are not on a line with the object


Tyndall effect: the phenomenon in which light is scattered by very small particles in its path; it makes a beam of light visible; the scattered light is mainly blue


heliocentric parallax: the parallax of a celestial body using two points in the earth's orbit around the sun as the baseline


annual parallax: the parallax of a celestial body using two points in the earth's orbit around the sun as the baseline


stellar parallax: the heliocentric parallax of a star


geocentric parallax: the parallax of a celestial body using two points on the surface of the earth as the earth rotates


diurnal parallax: the parallax of a celestial body using two points on the surface of the earth as the earth rotates


horizontal parallax: the maximum parallax observed when the celestial body is at the horizon


pulsation: a periodically recurring phenomenon that alternately increases and decreases some quantity


solar parallax: the angle subtended by the mean equatorial radius of the Earth at a distance of one astronomical unit


Plantae: (botany) the taxonomic kingdom comprising all living or extinct plants


kingdom Plantae: (botany) the taxonomic kingdom comprising all living or extinct plants


plant kingdom: (botany) the taxonomic kingdom comprising all living or extinct plants


microflora: microscopic plants; bacteria are often considered to be microflora


plant cell: a cell that is a structural and functional unit of a plant


cell wall: a rigid layer of polysaccharides enclosing the membrane of plant and prokaryotic cells; maintains the shape of the cell and serves as a protective barrier


crop: a cultivated plant that is grown commercially on a large scale


endemic: a plant that is native to a certain limited area


holophyte: an organism that produces its own food by photosynthesis


non-flowering plant: a plant that does not bear flowers


plantlet: a young plant or a small plant


wilding: a wild uncultivated plant (especially a wild apple or crabapple tree)


semi-climber: a plant that tends to climb and on occasion can grow like a vine


Thallophyta: used only in former classifications: comprising what is now considered a heterogeneous assemblage of flowerless and seedless organisms: algae; bacteria; fungi; lichens


thallophyte: any of a group of cryptogamic organisms consisting principally of a thallus and thus showing no differentiation into stem and root and leaf


button: any of various plant parts that resemble buttons


thallus: a plant body without true stems or roots or leaves or vascular system; characteristic of the thallophytes


crustose thallus: thin crusty lichen thallus; adheres closely to or is embedded in the surface on which it grows


cap: a fruiting structure resembling an umbrella or a cone that forms the top of a stalked fleshy fungus such as a mushroom


pileus: a fruiting structure resembling an umbrella or a cone that forms the top of a stalked fleshy fungus such as a mushroom


calyptra: the hood or cap covering the calyx of certain plants: e.g., the California poppy


volva: cuplike structure around the base of the stalk of certain fungi


ascocarp: mature fruiting body of an ascomycetous fungus


acervulus: small asexual fruiting body resembling a cushion or blister consisting of a mat of hyphae that is produced on a host by some fungi


basidiocarp: the fruiting body of a basidiomycete which bears its spores on special cells


peridium: outer layer of the spore-bearing organ in many fungi


ascoma: an ascocarp having the spore-bearing layer of cells (the hymenium) on a broad disklike receptacle


apothecium: a cuplike ascocarp in many lichens and ascomycetous fungi


cleistothecium: closed spore-bearing structure of some fungi (especially Aspergillaceae and Erysiphaceae) from which spores are released only by decay or disintegration


cleistocarp: closed spore-bearing structure of some fungi (especially Aspergillaceae and Erysiphaceae) from which spores are released only by decay or disintegration


domatium: a part of a plant (e.g., a leaf) that has been modified to provide protection for insects or mites or fungi


podetium: an organ or body resembling a stalk; especially the outgrowth of the thallus of certain lichens on which the ascocarp is borne


seta: stalk of a moss capsule


Tracheophyta: in former classifications: comprising plants with a vascular system including ferns and fern allies as well as seed plants


division Tracheophyta: in former classifications: comprising plants with a vascular system including ferns and fern allies as well as seed plants


plant order: the order of plants


ornamental: any plant grown for its beauty or ornamental value


pot plant: a plant suitable for growing in a flowerpot (especially indoors)


acrogen: any flowerless plant such as a fern (pteridophyte) or moss (bryophyte) in which growth occurs only at the tip of the main stem


apomict: a plant that reproduces or is reproduced by apomixis


aquatic: a plant that lives in or on water


Bryophyta: a division of nonflowering plants characterized by rhizoids rather than true roots and having little or no organized vascular tissue and showing alternation of generations between gamete-bearing forms and spore-bearing forms; comprises true mosses (Bryopsida) and liverworts (Hepaticopsida) and hornworts (Anthoceropsida)


division Bryophyta: a division of nonflowering plants characterized by rhizoids rather than true roots and having little or no organized vascular tissue and showing alternation of generations between gamete-bearing forms and spore-bearing forms; comprises true mosses (Bryopsida) and liverworts (Hepaticopsida) and hornworts (Anthoceropsida)


bryophyte: any of numerous plants of the division Bryophyta


nonvascular plant: any of numerous plants of the division Bryophyta


moss: tiny leafy-stemmed flowerless plants


moss family: a family of mosses


moss genus: a genus of mosses


Anthoceropsida: hornworts: in some classification systems included in the class Hepaticopsida


class Anthoceropsida: hornworts: in some classification systems included in the class Hepaticopsida


Anthocerotales: hornworts; liverworts having a thalloid gametophyte; in some classification systems included in the class Hepaticopsida


order Anthocerotales: hornworts; liverworts having a thalloid gametophyte; in some classification systems included in the class Hepaticopsida


Anthocerotaceae: hornworts


family Anthocerotaceae: hornworts


Anthoceros: hornworts


genus Anthoceros: hornworts


hornwort: liverworts with slender hornlike capsules


Bryopsida: true mosses: bryophytes having leafy rather than thalloid gametophytes: comprises orders Andreaeales; Bryales; Dicranales; Eubryales; Sphagnales


class Bryopsida: true mosses: bryophytes having leafy rather than thalloid gametophytes: comprises orders Andreaeales; Bryales; Dicranales; Eubryales; Sphagnales


Musci: true mosses: bryophytes having leafy rather than thalloid gametophytes: comprises orders Andreaeales; Bryales; Dicranales; Eubryales; Sphagnales


class Musci: true mosses: bryophytes having leafy rather than thalloid gametophytes: comprises orders Andreaeales; Bryales; Dicranales; Eubryales; Sphagnales


acrocarp: a moss in which the main axis is terminated by the archegonium (and hence the capsule)


acrocarpous moss: a moss in which the main axis is terminated by the archegonium (and hence the capsule)


pleurocarp: a moss having the archegonium or antheridium on a short side branch rather than the main stalk


pleurocarpous moss: a moss having the archegonium or antheridium on a short side branch rather than the main stalk


Andreaeales: comprises a single genus: Andreaea


order Andreaeales: comprises a single genus: Andreaea


Andreaea: brown or blackish Alpine mosses having a dehiscent capsule with 4 longitudinal slits


genus Andreaea: brown or blackish Alpine mosses having a dehiscent capsule with 4 longitudinal slits


Bryales: category used in some classification systems for mosses having the spore case separated from the capsule wall by a hollow intercellular space


order Bryales: category used in some classification systems for mosses having the spore case separated from the capsule wall by a hollow intercellular space


Dicranales: widely distributed order of mosses with erect gametophores and sporophytes at the tips of stems


order Dicranales: widely distributed order of mosses with erect gametophores and sporophytes at the tips of stems


Dicranaceae: mosses having costate leaves and long-stalked capsules with cleft peristome


family Dicranaceae: mosses having costate leaves and long-stalked capsules with cleft peristome


Dicranum: type genus of Dicranaceae


genus Dicranum: type genus of Dicranaceae


Eubryales: mosses with perennial erect gametophores and stems with rows of leaves and drooping capsules


order Eubryales: mosses with perennial erect gametophores and stems with rows of leaves and drooping capsules


Bryaceae: a family of acrocarpous mosses


family Bryaceae: a family of acrocarpous mosses


Bryum: type genus of the Bryaceae: mosses distinguished by mostly erect and tufted gametophytes and symmetrical short-necked capsules


genus Bryum: type genus of the Bryaceae: mosses distinguished by mostly erect and tufted gametophytes and symmetrical short-necked capsules


Mniaceae: family of erect mosses with club-shaped paraphyses and the hexagonal cells of the upper leaf surface; sometimes treated as a subfamily of Bryaceae


family Mniaceae: family of erect mosses with club-shaped paraphyses and the hexagonal cells of the upper leaf surface; sometimes treated as a subfamily of Bryaceae


Mnium: mosses similar to those of genus Bryum but larger


genus Mnium: mosses similar to those of genus Bryum but larger


Sphagnales: coextensive with the genus Sphagnum; in some classifications isolated in a separate subclass


order Sphagnales: coextensive with the genus Sphagnum; in some classifications isolated in a separate subclass


genus Sphagnum: a large genus constituting the order Sphagnales: atypical mosses of temperate bogs with leaves that can hold much water


sphagnum: any of various pale or ashy mosses of the genus Sphagnum whose decomposed remains form peat


sphagnum moss: any of various pale or ashy mosses of the genus Sphagnum whose decomposed remains form peat


peat moss: any of various pale or ashy mosses of the genus Sphagnum whose decomposed remains form peat


bog moss: any of various pale or ashy mosses of the genus Sphagnum whose decomposed remains form peat


Hepaticopsida: liverworts: comprises orders Anthocerotales; Jungermanniales; Marchantiales; Sphaerocarpales


class Hepaticopsida: liverworts: comprises orders Anthocerotales; Jungermanniales; Marchantiales; Sphaerocarpales


Hepaticae: liverworts: comprises orders Anthocerotales; Jungermanniales; Marchantiales; Sphaerocarpales


class Hepaticae: liverworts: comprises orders Anthocerotales; Jungermanniales; Marchantiales; Sphaerocarpales


liverwort: any of numerous small green nonvascular plants of the class Hepaticopsida growing in wet places and resembling green seaweeds or leafy mosses


hepatic: any of numerous small green nonvascular plants of the class Hepaticopsida growing in wet places and resembling green seaweeds or leafy mosses


Jungermanniales: large order of chiefly tropical liverworts


order Jungermanniales: large order of chiefly tropical liverworts


leafy liverwort: moss-like liverwort with tiny scalelike leaves; usually epiphytic


scale moss: moss-like liverwort with tiny scalelike leaves; usually epiphytic


Jungermanniaceae: comprising the leafy members of the order Jungermanniales


family Jungermanniaceae: comprising the leafy members of the order Jungermanniales


Marchantiales: liverworts with gametophyte differentiated internally


order Marchantiales: liverworts with gametophyte differentiated internally


Marchantiaceae: liverworts with prostrate and usually dichotomously branched thalli


family Marchantiaceae: liverworts with prostrate and usually dichotomously branched thalli


Marchantia: type genus of Marchantiaceae; liverworts that reproduce asexually by gemmae and have stalked antheridiophores


genus Marchantia: type genus of Marchantiaceae; liverworts that reproduce asexually by gemmae and have stalked antheridiophores


hepatica: a common liverwort


Marchantia polymorpha: a common liverwort


Sphaerocarpales: small order sometimes included in the order Jungermanniales


order Sphaerocarpales: small order sometimes included in the order Jungermanniales


Sphaerocarpaceae: liverworts with bilaterally symmetrical gametophytes; sometimes placed in the order Jungermanniales


family Sphaerocarpaceae: liverworts with bilaterally symmetrical gametophytes; sometimes placed in the order Jungermanniales


Sphaerocarpus: type genus of Sphaerocarpaceae; liverworts with small many-lobed usually orbicular thallus


genus Sphaerocarpus: type genus of Sphaerocarpaceae; liverworts with small many-lobed usually orbicular thallus


Sphaerocarpos: type genus of Sphaerocarpaceae; liverworts with small many-lobed usually orbicular thallus


genus Sphaerocarpos: type genus of Sphaerocarpaceae; liverworts with small many-lobed usually orbicular thallus


Pteridophyta: containing all the vascular plants that do not bear seeds: ferns, horsetails, club mosses, and whisk ferns; in some classifications considered a subdivision of Tracheophyta


division Pteridophyta: containing all the vascular plants that do not bear seeds: ferns, horsetails, club mosses, and whisk ferns; in some classifications considered a subdivision of Tracheophyta


genus Pecopteris: genus of Carboniferous fossil ferns


pecopteris: Carboniferous fossil fern characterized by a regular arrangement of the leaflets resembling a comb


pteridophyte: plants having vascular tissue and reproducing by spores


nonflowering plant: plants having vascular tissue and reproducing by spores


fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores


fern ally: pteridophytes of other classes than Filicopsida


agamete: an asexual reproductive cell


spore: a small usually single-celled asexual reproductive body produced by many nonflowering plants and fungi and some bacteria and protozoans and that are capable of developing into a new individual without sexual fusion


basidiospore: a sexually produced fungal spore borne on a basidium


endospore: a small asexual spore that develops inside the cell of some bacteria and algae


carpospore: a nonmotile spore of red algae


chlamydospore: thick-walled asexual resting spore of certain fungi and algae


conidium: an asexually produced fungal spore formed on a conidiophore


conidiospore: an asexually produced fungal spore formed on a conidiophore


conidiophore: a specialized fungal hypha that produces conidia


oospore: a thick-walled sexual spore that develops from a fertilized oosphere in some algae and fungi


oosphere: a gamete; used especially of lower plants


resting spore: a spore of certain algae or fungi that lies dormant; may germinate after a prolonged period


teliospore: a chlamydospore that develops in the last stage of the life cycle of the rust fungus


tetraspore: one of the four asexual spores produced within a sporangium


zoospore: an asexual spore of some algae and fungi that moves by means of flagella


fern seed: the asexual spore of ferns that resembles dust; once thought to be seeds and to make the possessor invisible


fructification: organs of fruiting (especially the reproductive parts of ferns and mosses)


gleba: fleshy spore-bearing inner mass of e.g. a puffball or stinkhorn


hymenium: spore-bearing layer of cells in certain fungi containing asci or basidia


pycnidium: flask-shaped asexual structure containing conidia


sporocarp: specialized leaf branch in certain aquatic ferns that encloses the sori or clusters of sporangia


spore case: specialized leaf branch in certain aquatic ferns that encloses the sori or clusters of sporangia


stipule: a small leafy outgrowth at the base of a leaf or its stalk; usually occurring in pairs and soon shed


tepal: an undifferentiated part of a perianth that cannot be distinguished as a sepal or a petal (as in lilies and tulips)


Spermatophyta: seed plants; comprises the Angiospermae (or Magnoliophyta) and Gymnospermae (or Gymnospermophyta); in some classification systems Spermatophyta is coordinate with Pteridophyta (spore producing plants having vascular tissue and roots) and Bryophyta (spore producing plants lacking vascular tissue and roots)


division Spermatophyta: seed plants; comprises the Angiospermae (or Magnoliophyta) and Gymnospermae (or Gymnospermophyta); in some classification systems Spermatophyta is coordinate with Pteridophyta (spore producing plants having vascular tissue and roots) and Bryophyta (spore producing plants lacking vascular tissue and roots)


Phanerogamae: in former classification systems: one of two major plant divisions, including all seed-bearing plants; superseded by the division Spermatophyta


Cryptogamia: in former classification systems: one of two major plant divisions, including all plants that do not bear seeds: ferns, mosses, algae, fungi


cryptogam: formerly recognized taxonomic group including all flowerless and seedless plants that reproduce by means of spores: ferns, mosses, algae, fungi


spermatophyte: plant that reproduces by means of seeds not spores


phanerogam: plant that reproduces by means of seeds not spores


seed plant: plant that reproduces by means of seeds not spores


seedling: young plant or tree grown from a seed


balsam: any seed plant yielding balsam


annual: (botany) a plant that completes its entire life cycle within the space of a year


biennial: (botany) a plant having a life cycle that normally takes two seasons from germination to death to complete; flowering biennials usually bloom and fruit in the second season


perennial: (botany) a plant lasting for three seasons or more


escape: a plant originally cultivated but now growing wild


hygrophyte: a plant that grows in a moist habitat


neophyte: a plant that is found in an area where it had not been recorded previously


gymnosperm family: a family of gymnosperms


gymnosperm genus: a genus of gymnosperms


monocot family: family of flowering plants having a single cotyledon (embryonic leaf) in the seed


liliopsid family: family of flowering plants having a single cotyledon (embryonic leaf) in the seed


liliid monocot family: family of monocotyledonous plants of the subclass Liliidae; mostly herbs usually with petaloid sepals and petals and compound pistils


monocot genus: genus of flowering plants having a single cotyledon (embryonic leaf) in the seed


liliopsid genus: genus of flowering plants having a single cotyledon (embryonic leaf) in the seed


liliid monocot genus: genus of monocotyledonous plants comprising mostly herbs having usually petaloid sepals and petals and compound pistils


dicot family: family of flowering plants having two cotyledons (embryonic leaves) in the seed which usually appear at germination


magnoliopsid family: family of flowering plants having two cotyledons (embryonic leaves) in the seed which usually appear at germination


magnoliid dicot family: family of dicotyledonous flowering plants regarded as among the most primitive of extant angiosperms


hamamelid dicot family: family of mostly woody dicotyledonous flowering plants with flowers often unisexual and often borne in catkins


caryophylloid dicot family: family of relatively early dicotyledonous plants including mostly flowers


dilleniid dicot family: family of more or less advanced dicotyledonous trees and shrubs and herbs


asterid dicot family: family of more or less advanced dicotyledonous herbs and some trees and shrubs


rosid dicot family: a family of dicotyledonous plants


dicot genus: genus of flowering plants having two cotyledons (embryonic leaves) in the seed which usually appear at germination


magnoliopsid genus: genus of flowering plants having two cotyledons (embryonic leaves) in the seed which usually appear at germination


magnoliid dicot genus: genus of dicotyledonous flowering plants regarded as among the most primitive of extant angiosperms


hamamelid dicot genus: genus of mostly woody relatively primitive dicotyledonous flowering plants with flowers often unisexual and often borne in catkins


caryophylloid dicot genus: genus of relatively early dicotyledonous plants including mostly flowers


dilleniid dicot genus: genus of more or less advanced dicotyledonous trees and shrubs and herbs


asterid dicot genus: genus of more or less advanced dicotyledonous herbs and some trees and shrubs


rosid dicot genus: a genus of dicotyledonous plants


fungus family: includes lichen families


fungus genus: includes lichen genera


fungus order: the order of fungi


Gymnospermae: plants having naked seeds not enclosed in an ovary; in some systems considered a class (Gymnospermae) and in others a division (Gymnospermophyta); comprises three subdivisions (or classes): Cycadophytina (class Cycadopsida) and Gnetophytina (class Gnetopsida) and Coniferophytina (class Coniferopsida); in some classifications the Coniferophytina are divided into three groups: Pinophytina (class Pinopsida) and Ginkgophytina (class Ginkgopsida) and Taxophytina (class Taxopsida)


class Gymnospermae: plants having naked seeds not enclosed in an ovary; in some systems considered a class (Gymnospermae) and in others a division (Gymnospermophyta); comprises three subdivisions (or classes): Cycadophytina (class Cycadopsida) and Gnetophytina (class Gnetopsida) and Coniferophytina (class Coniferopsida); in some classifications the Coniferophytina are divided into three groups: Pinophytina (class Pinopsida) and Ginkgophytina (class Ginkgopsida) and Taxophytina (class Taxopsida)


Gymnospermophyta: plants having naked seeds not enclosed in an ovary; in some systems considered a class (Gymnospermae) and in others a division (Gymnospermophyta); comprises three subdivisions (or classes): Cycadophytina (class Cycadopsida) and Gnetophytina (class Gnetopsida) and Coniferophytina (class Coniferopsida); in some classifications the Coniferophytina are divided into three groups: Pinophytina (class Pinopsida) and Ginkgophytina (class Ginkgopsida) and Taxophytina (class Taxopsida)


division Gymnospermophyta: plants having naked seeds not enclosed in an ovary; in some systems considered a class (Gymnospermae) and in others a division (Gymnospermophyta); comprises three subdivisions (or classes): Cycadophytina (class Cycadopsida) and Gnetophytina (class Gnetopsida) and Coniferophytina (class Coniferopsida); in some classifications the Coniferophytina are divided into three groups: Pinophytina (class Pinopsida) and Ginkgophytina (class Ginkgopsida) and Taxophytina (class Taxopsida)


gymnosperm: plants of the class Gymnospermae having seeds not enclosed in an ovary


progymnosperm: an ancestral fossil type from which modern gymnosperms are thought to have derived


Gnetopsida: gymnospermous flowering plants; supposed link between conifers and angiosperms; in some systems classified as a class (Gnetopsida) and in others as a subdivision (Gnetophytina or Gnetophyta)


class Gnetopsida: gymnospermous flowering plants; supposed link between conifers and angiosperms; in some systems classified as a class (Gnetopsida) and in others as a subdivision (Gnetophytina or Gnetophyta)


Gnetophytina: gymnospermous flowering plants; supposed link between conifers and angiosperms; in some systems classified as a class (Gnetopsida) and in others as a subdivision (Gnetophytina or Gnetophyta)


subdivision Gnetophytina: gymnospermous flowering plants; supposed link between conifers and angiosperms; in some systems classified as a class (Gnetopsida) and in others as a subdivision (Gnetophytina or Gnetophyta)


Gnetophyta: gymnospermous flowering plants; supposed link between conifers and angiosperms; in some systems classified as a class (Gnetopsida) and in others as a subdivision (Gnetophytina or Gnetophyta)


Gnetales: chiefly tropical or xerophytic woody plants; practically unknown as fossils but considered close to the ancestral line of angiosperms


order Gnetales: chiefly tropical or xerophytic woody plants; practically unknown as fossils but considered close to the ancestral line of angiosperms


Gnetaceae: plants having small unisexual flowers and fleshy or winged fruit: in some classifications includes the genera Ephedra and Welwitschia as well as genus Gnetum


family Gnetaceae: plants having small unisexual flowers and fleshy or winged fruit: in some classifications includes the genera Ephedra and Welwitschia as well as genus Gnetum


genus Gnetum: type genus of the Gnetaceae; small trees or shrubs usually with climbing jointed stems and terminal spikes of flowers with orange-red seeds clustered in rough cones


gnetum: small tropical tree with tiered branches and divaricate branchlets having broad glossy dark green leaves; exploited for its edible young leaves and seeds that provide a fine flour


Gnetum gnemon: small tropical tree with tiered branches and divaricate branchlets having broad glossy dark green leaves; exploited for its edible young leaves and seeds that provide a fine flour


Ephedraceae: ephedras: in some classifications included in the Gnetaceae


family Ephedraceae: ephedras: in some classifications included in the Gnetaceae


Catha: a genus of African evergreen shrubs characterized by thick leaves and white flowers


genus Catha: a genus of African evergreen shrubs characterized by thick leaves and white flowers


Catha edulis: a shrub that is cultivated by Arabs for its leaves which are chewed or used to make tea


genus Ephedra: type and sole genus of Ephedraceae: tropical and subtropical evergreen shrubby or creeping plants native to dry and inhospitable regions


ephedra: jointed and nearly leafless desert shrub having reduced scalelike leaves and reddish fleshy seeds


joint fir: jointed and nearly leafless desert shrub having reduced scalelike leaves and reddish fleshy seeds


mahuang: Chinese ephedra yielding ephedrine


Ephedra sinica: Chinese ephedra yielding ephedrine


Welwitschiaceae: in some classifications included in the Gnetaceae


family Welwitschiaceae: in some classifications included in the Gnetaceae


genus Welwitschia: type and sole genus of Welwitschiaceae


genus Welwitchia: type and sole genus of Welwitschiaceae


welwitschia: curious plant of arid regions of southwestern Africa having a yard-high and yard-wide trunk like a turnip with a deep taproot and two large persistent woody straplike leaves growing from the base; living relic of a flora long disappeared; some may be 700-5000 years old


Welwitschia mirabilis: curious plant of arid regions of southwestern Africa having a yard-high and yard-wide trunk like a turnip with a deep taproot and two large persistent woody straplike leaves growing from the base; living relic of a flora long disappeared; some may be 700-5000 years old


Cycadopsida: palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)


class Cycadopsida: palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)


Cycadophytina: palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)


subdivision Cycadophytina: palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)


Cycadophyta: palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)


subdivision Cycadophyta: palmlike gymnosperms: includes the surviving order Cycadales and several extinct orders; possibly not a natural group; in some systems considered a class (Cycadopsida) and in others a subdivision (Cycadophytina or Cycadophyta)


Cycadales: primitive tropical gymnosperms abundant in the Mesozoic, now reduced to a few scattered tropical forms


order Cycadales: primitive tropical gymnosperms abundant in the Mesozoic, now reduced to a few scattered tropical forms


cycad: any tropical gymnosperm of the order Cycadales; having unbranched stems with a crown of fernlike leaves


Cycadaceae: ancient palmlike plants closely related to ferns in that fertilization is by means of spermatozoids


family Cycadaceae: ancient palmlike plants closely related to ferns in that fertilization is by means of spermatozoids


cycad family: ancient palmlike plants closely related to ferns in that fertilization is by means of spermatozoids


Cycas: type genus of Cycadaceae: genus of widely distributed Old World evergreen tropical trees having pinnate leaves and columnar stems covered with persistent bases of old leaves


genus Cycas: type genus of Cycadaceae: genus of widely distributed Old World evergreen tropical trees having pinnate leaves and columnar stems covered with persistent bases of old leaves


sago palm: dwarf palmlike cycad of Japan that yields sago


Cycas revoluta: dwarf palmlike cycad of Japan that yields sago


false sago: southeastern Indian cycad with palmlike foliage


fern palm: southeastern Indian cycad with palmlike foliage


Cycas circinalis: southeastern Indian cycad with palmlike foliage


Zamiaceae: a family of cycads often included in the family Cycadaceae: zamias


family Zamiaceae: a family of cycads often included in the family Cycadaceae: zamias


zamia family: a family of cycads often included in the family Cycadaceae: zamias


genus Zamia: genus of small evergreen tropical and subtropical American cycads


zamia: any of various cycads of the genus Zamia; among the smallest and most verdant cycads


coontie: small tough woody zamia of Florida and West Indies and Cuba; roots and half-buried stems yield an arrowroot


Florida arrowroot: small tough woody zamia of Florida and West Indies and Cuba; roots and half-buried stems yield an arrowroot


Seminole bread: small tough woody zamia of Florida and West Indies and Cuba; roots and half-buried stems yield an arrowroot


Zamia pumila: small tough woody zamia of Florida and West Indies and Cuba; roots and half-buried stems yield an arrowroot


genus Ceratozamia: small genus of Mexican cycads; sometimes classified in family Cycadaceae


ceratozamia: a small cycad of the genus Ceratozamia having a short scaly woody trunk and fernlike foliage and woody cones; Mexico


genus Dioon: small genus of arborescent cycads of Mexico and Central America; sometimes classified in family Cycadaceae


dioon: any cycad of the genus Dioon; handsome palmlike cycads with robust crowns of leaves and rugged trunks


genus Encephalartos: genus of arborescent African cycads; sometimes classified in family Cycadaceae


encephalartos: any of numerous cycads of the genus Encephalartos having stout cylindrical trunks and a terminal crown of long often spiny pinnate leaves


kaffir bread: South African cycad; the farinaceous pith of the fruit used as food


Encephalartos caffer: South African cycad; the farinaceous pith of the fruit used as food


genus Macrozamia: genus of large evergreen Australian cycads; sometimes classified in family Cycadaceae


macrozamia: any treelike cycad of the genus Macrozamia having erect trunks and pinnate leaves and large cones with sometimes edible nuts; Australia


burrawong: large attractive palmlike evergreen cycad of New South Wales


Macrozamia communis: large attractive palmlike evergreen cycad of New South Wales


Macrozamia spiralis: large attractive palmlike evergreen cycad of New South Wales


Bennettitales: fossil gymnospermous plants of the Carboniferous


order Bennettitales: fossil gymnospermous plants of the Carboniferous


Bennettitaceae: a family of fossil gymnospermous plants of the Carboniferous


family Bennettitaceae: a family of fossil gymnospermous plants of the Carboniferous


Bennettitis: type of the Bennettitales


genus Bennettitis: type of the Bennettitales


Pteridospermopsida: extinct gymnosperms most of Carboniferous to Jurassic: seed ferns and allies


class Pteridospermopsida: extinct gymnosperms most of Carboniferous to Jurassic: seed ferns and allies


Cycadofilicales: fossil gymnospermous trees or climbing plants from the Devonian: seed ferns


order Cycadofilicales: fossil gymnospermous trees or climbing plants from the Devonian: seed ferns


Lyginopteridales: fossil gymnospermous trees or climbing plants from the Devonian: seed ferns


order Lyginopteridales: fossil gymnospermous trees or climbing plants from the Devonian: seed ferns


Pteridospermae: used in some classification systems: a group of extinct fossil gymnosperms coextensive with the order Cycadofilicales


group Pteridospermae: used in some classification systems: a group of extinct fossil gymnosperms coextensive with the order Cycadofilicales


Pteridospermaphyta: used in some classification systems: a group of extinct fossil gymnosperms coextensive with the order Cycadofilicales


group Pteridospermaphyta: used in some classification systems: a group of extinct fossil gymnosperms coextensive with the order Cycadofilicales


Lyginopteris: genus of fossil seed ferns of the Carboniferous


genus Lyginopteris: genus of fossil seed ferns of the Carboniferous


seed fern: an extinct seed-producing fernlike plant of the order Cycadofilicales (or group Pteridospermae)