Homonym

In linguistics, homonyms, broadly defined, are words which are homographs (words that share the same spelling, regardless of pronunciation) or homophones (words that share the same pronunciation, regardless of spelling), or both. For example, according to this definition, the words "row" (propel with oars), "row" (argument) and "row" (a linear arrangement) are homonyms, as are the words "see" (vision) and "sea" (body of water).
A more restrictive or technical definition sees homonyms as words that are simultaneously homographs "and" homophones – that is to say they have identical spelling "and" pronunciation, whilst maintaining different meanings. Examples are the pair "stalk" (part of a plant) and "stalk" (follow/harass a person) and the pair "left" (past tense of leave) and "left" (opposite of right). 
A distinction is sometimes made between true homonyms, which are unrelated in origin, such as "skate" (glide on ice) and "skate" (the fish), and polysemous homonyms, or polysemes, which have a shared origin, such as "mouth" (of a river) and "mouth" (of an animal).
The relationship between a set of homonyms is called homonymy, and the associated adjective is homonymous or homonymic.
The adjective "homonymous" can additionally be used wherever two items share the same name, independent of how closely they are or are not related in terms of their meaning or etymology. For example, the name Ōkami is homonymous with the Japanese term for "wolf" (Ōkami).
Etymology.
The word "homonym" comes from the Greek ὁμώνυμος ("homonymos"), meaning "having the same name", which is the conjunction of ὁμός ("homos"), "common, same,
similar " and ὄνομα ("onoma") meaning "name". Thus, it refers to two or more distinct concepts sharing the "same name" or signifier. Note: for the "h" sound, see rough breathing and smooth breathing.
Related terms.
Several similar linguistic concepts are related to homonymy. These include:
Further examples.
The word with the greatest number of definitions in the English language is: Set
below are some examples:
A further example of a homonym, which is both a homophone and a homograph, is fluke. Fluke can mean:
These meanings represent at least three etymologically separate lexemes, but share the one form, fluke.* Note that fluke is also a capitonym, in that Fluke Corporation (commonly referred to as simply "Fluke") is a manufacturer of industrial testing equipment.
Similarly, a river bank, a savings bank, a bank of switches, and a bank shot in the game of pool share a common spelling and pronunciation, but differ in meaning.
The words bow and bough are examples where there are two meanings associated with a single pronunciation and spelling (the weapon and the knot); two meanings with two different pronunciations (the knot and the act of bending at the waist), and two distinct meanings sharing the same sound but different spellings (bow, the act of bending at the waist, and bough, the branch of a tree). In addition, it has several related but distinct meanings – a bent line is sometimes called a 'bowed' line, reflecting its similarity to the weapon. Even according to the most restrictive definitions, various pairs of sounds and meanings of bow, Bow and bough are homonyms, homographs, homophones, heteronyms, heterographs, capitonyms and are polysemous.
A lime can refer to a fruit or a material. A mold (mould) can refer to a fungus or an industrial cast.
The words "there", "their", and "they're" are examples of three words that are of a singular pronunciation, have different spellings and vastly different meanings. These three words are commonly misused (or misspelled if you want to look at it that way).
Homonyms in historical linguistics.
Homonymy can lead to communicative conflicts and thus trigger lexical (onomasiological) change. This is known as "homonymic conflict".