Lexeme (i.e. set of word-forms)
A lexeme is usually defined as a set of inflected word-forms that differ only in their inflectional properties. As it is usually assumed that not all regularly formed word-forms are listed in the lexicon, a lexeme in this sense is a lexical item, while a word-form is not (normally).
- "a lexeme is a (potential o actual) member of a major lexical category, having both form and meaning but being neither, and existing outside of any particular syntactic context" (Aronoff 1994:11)
The English word-forms boy and boys make up the lexeme BOY. The Latin word-forms habeo 'I have', habes 'you have', habet 's/he has', habemus 'we have', habebam 'I had', habebunt 'they will have', and so on make up the lexeme HABERE.
This particular use of the term lexeme sems to have its roots in Matthews (1972).