In linguistics, homonyms are words which are homographs (words that share the same spelling, regardless of pronunciation), or homophones (equivocal words, that share the same pronunciation, regardless of spelling), or both. Using this definition, the words row (propel with oars), row (a linear arrangement) and row (an argument) are homonyms because they are homographs (though only the first two are homophones): so are the words see (vision) and sea (body of water), because they are homophones (though not homographs).
A more restrictive and technical definition requires that homonyms be simultaneously homographs and homophones – that is to say they have identical spelling and pronunciation, but with 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, homonymic, or in latin, equivocal.
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).
The word homonym comes from the Greek ὁμώνυμος (homonymos), meaning "having the same name", compounded from ὁμός (homos) 'common, same, similar' and ὄνομα (onoma) 'name'.
|Homophone word||Different||(No requirement)||Same|
|Homophone phrase||Different||Different||Same to varying degree|
|Polyseme||Different but related||Same||(No requirement)|
|Same except for
Several similar linguistic concepts are related to homonymy. These include:
A homonym which is both a homophone and a homograph is fluke, meaning:
These meanings represent at least three etymologically separate lexemes, but share the one form, fluke.* 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, alternatively, misspelled).
The words metal and mettle are polysemes and homophones, but not homographs.
Homonymy can lead to communicative conflicts and thus trigger lexical (onomasiological) change. This is known as homonymic conflict. This leads to a species of informal fallacy of thought and argument called by the latin name equivocation.
I suggest that words similar in sound but different in meaning should be referred to as synophones (cf. synonym = word of similar meaning).