NOUN (1)

1. a minimal unit (as a word or stem) in the lexicon of a language; `go'; and `went'; and `gone'; and `going'; are all members of the English lexeme `go';

WordNet (r) 3.0 (2006):

lexeme
    n 1: a minimal unit (as a word or stem) in the lexicon of a
         language; `go' and `went' and `gone' and `going' are all
         members of the English lexeme `go'

The Free On-line Dictionary of Computing (19 January 2023):

lexeme

    A minimal lexical unit of a language.  Lexical
   analysis converts strings in a language into a list of
   lexemes.  For a programming language these word-like pieces
   would include keywords, identifiers, literals and
   punctuation.  The lexemes are then passed to the parser for
   syntactic analysis.

   (1996-04-06)