laxative (adj.)
late 14c., "causing relaxation or looseness," from Old French laxatif (13c.), from Medieval Latin laxativus "loosening," from Latin laxat-, past participle stem of laxare "loosen," from laxus "loose, lax" (see lax). The noun meaning "a laxative medicine, a medicine that relieves constipation by relaxing the intestines" is from late 14c.
aperitif (n.)
"alcoholic drink taken before a meal to stimulate the appetite," 1890, from French apéritif "laxative, laxative liqueur," literally "opening," from Latin aperitivus, from aperire "to open, uncover," from PIE compound *ap-wer-yo- from *ap- "off, away" (see apo-) + root *wer- (4) "to cover." A doublet of apertive.
apertive (n.)
"medicine capable of opening or dilating" (pores, bowels, etc.), "a laxative," early 15c., also as an adjective, from Latin aperitivus, from aperire "to open, uncover," from PIE compound *ap-wer-yo- from *ap- "off, away" (see apo-) + root *wer- (4) "to cover." Also aperient (1620s).
treacle (n.)
mid-14c., "medicinal compound, antidote for poison," from Old French triacle "antidote, cure for snake-bite" (c. 1200), from Vulgar Latin *triacula, from Latin theriaca, from Greek theriake (antidotos) "antidote for poisonous wild animals," from fem. of theriakos "of a wild animal," from therion "wild animal," diminutive of ther (genitive theros) "wild animal," from PIE root *ghwer- "wild beast."
Sense of "molasses" is first recorded 1690s (the connection may be from the use of molasses as a laxative, or its use to disguise the bad taste of medicine); that of "anything too sweet or sentimental" is from 1771. Related: Treacly.
physic (n.)
c. 1300, fysike, phisike, "a healing potion;" early 14c., "natural science;" mid-14c. "healthful regimen;" late 14c., "the art of healing, medical science or theory;" from Old French fisike "natural science, art of healing" (12c.) and directly from Latin physica (fem. singular of physicus) "study of nature," from Greek physikē (epistēmē) "(knowledge) of nature," from fem. of physikos "pertaining to nature," from physis "nature," from phyein "to bring forth, produce, make to grow" (related to phyton "growth, plant," phylē "tribe, race," phyma "a growth, tumor") from PIE root *bheue- "to be, exist, grow."
The English spelling with ph- is attested from late 14c. (see ph). The meaning "medicine that acts as a laxative" is from 1610s. The obsolete verb meaning "to dose with medicine, administer medical treatment to" is attested from late 14c. (phisiken).
purge (v.)
c. 1300, purgen, "clear of a charge or suspicion," from Anglo-French purger, Old French purgier "wash, clean; refine, purify" morally or physically (12c., Modern French purger) and directly from Latin purgare "cleanse, make clean; purify," especially in reference to the body, "free from what is superfluous; remove, clear away," but also figuratively "refute, justify, vindicate," from Old Latin purigare, from purus "pure" (see pure) + root of agere "to set in motion, drive; to do, perform" (from PIE root *ag- "to drive, draw out or forth, move").
By mid-14c. as "to cleanse (a person or soul) from sin or moral defilement; to cleanse, clear, purify" (metal, etc.), also medicinally "to cleanse the body or digestive tract by a laxative, diuretic, or emetic." The figurative sense of "make ideal or pure, rid of objectionable elements or members" is by 1580s. Related: Purged; purging. The Latin verb is also the source of Spanish purgar, Italian purgare.
castor (n.)
late 14c., "a beaver," from Old French castor (13c.), from Latin castor "beaver," from Greek kastor "beaver," literally "he who excels," also the name of one of the divine twins (with Pollux), worshipped by women in ancient Greece as a healer and preserver from disease.
It has been assumed that the hero's name was given to the animal because he was a noted healer and the odorous reddish-brown secretions of the inguinal sacs of the animal (Latin castoreum), were used medicinally in ancient times, especially for women's diseases. But the animal did not live in Greece in classical times (the closest beavers were north of the Black Sea), and the name probably was borrowed from another language, perhaps influenced by the hero's name. The Greek word replaced the native Latin word for "beaver" (fiber).
In English, castor is attested in the secretion sense from late 14c. Modern castor oil is first recorded 1746; it is made from seeds of the plant Ricinus communis but supposedly possesses the laxative qualities (and taste) of beaver juice.
powder (n.)
"fine, minute, loose, uncompacted particles," c. 1300, poudre, "ash, cinders; dust of the earth;" early 14c. of any pulverized substance; from Old French poudre "dust, powder; ashes; powdered substance" (13c.), earlier pouldre (11c.), from Latin pulverem (nominative pulvis) "dust, powder" (source also of Spanish polvo, Italian polve; see pulverize).
The insertion of the unetymological -d- was common in French (compare meddle, tender (adj.), remainder). German has it as a doublet; Puder via French and Pulver from Latin. From mid-14c. specifically as "medicinal powder;" specialized sense of "gunpowder" is from late 14c. In the sense "powdered cosmetic," it is recorded from 1570s.
Powder keg "small barrel for holding gunpowder" is by 1820; the figurative sense ("something likely to explode easily") is by 1895. Powder room, euphemistic for "women's lavatory," is attested from 1936. Earlier it meant "place where gunpowder is stored on a warship" (1620s). Powder monkey "boy employed on ships to carry powder from the magazines to the guns" is from 1680s. Powder blue (1650s) was smalt used in laundering; as a color name from 1894.
The phrase take a powder "scram, vanish," is from 1920; it was a common phrase as a doctor's instruction, so perhaps the notion is of taking a laxative medicine or a sleeping powder, with the result that one has to leave in a hurry (or, on another guess, from a magician's magical powder, which makes things disappear).
Avis dropped an exhausted little heap onto her aunt's bed. She put her hand over her heart and said piteously, "Oh, Aunt Joyce, I mustn't ever do that again. My heart's going awful fast. I shall have to take a powder. Wasn't it fun though-" Avis' dark eyes flashed. [from "The Evolution of Avis" in The Connecticut School Journal, Jan. 9, 1902]
When the wife of your breast has confessed she has drest
On just triple the sum you allowed her,
And has run up long bills for her frocks and her frills—
Take a powder, my friend, take a powder.
[from "The Panacaea," in Punch, Dec. 14, 1901]
Powder in the wind (c. 1300, meaning powdered spices) was a Middle English image of something highly valued but flawed in some way that renders it impermanent or doomed to loss (of virtues without humility, etc.).