Meaning

noun 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'

originFrom Latin lexis, from Ancient Greek λέξις (léxis, “word”) + -eme, a suffix indicating a fundamental unit in some aspect of linguistic structure, on the model of phoneme.

Etymology from Wiktionary, CC BY-SA 3.0