LEXEME, also lexical item, lexical unit. In LINGUISTICS, a unit in the LEXICON or VOCABULARY of a language. Its form is governed by sound and writing or print, its content by meaning and use. Thus, penicillin is the realization in print of a single English lexeme, while the nouns crane and bank represent at least two lexemes each: crane (a particular bird and a particular machine), bank (the shore of a river and a particular kind of financial institution). Most English dictionaries treat crane n. as a single headword with two senses (a case of POLYSEMY) and bank n. as two headwords, each with at least one sense: a case of HOMONYMY. Conventionally, a lexeme's inflections (such as cranes, banks) are considered variant forms, whereas such derivatives as banker are considered separate lexemes. In English as in other languages, lexemes may be single words (crane, bank), parts of words (auto-, -logy), groups of words (the compound blackbird and the idiom kick the bucket), or shortened forms (flu for influenza, UK for United Kingdom). See LEXICOLOGY, MORPHEME.

lex·eme / ˈlekˌsēm/ • n. Linguistics a basic lexical unit of a language, consisting of one word or several words, considered as an abstract unit, and applied to a family of words related by form or meaning.