Meaning

noun the distinct personality of an individual regarded as a persisting entity

noun the individual characteristics by which a thing or person is recognized or known

noun an operator that leaves unchanged the element on which it operates

originFrom Middle English ydemptite, from Middle French identité and its etymon Late Latin idemptitās, identitās, from idem (“the same”) + -tās (suffix forming abstract nouns) as a calque of Ancient Greek ταὐτότης (tautótēs, “sameness”).

Etymology from Wiktionary, CC BY-SA 3.0