From 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”).^[1][2]

• (Received Pronunciation) IPA^(key): /aɪˈdɛntɪti/
• (General American) IPA^(key): /aɪˈdɛn(t)ɪti/, /aɪˈdɛn(t)əti/, [aɪˈdɛnɪɾi], [aɪˈdɛnəɾi]
• (General Australian) IPA^(key): /ɑɪˈdentəti/

  • Audio (General Australian):

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• Audio (US):

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identity (countable and uncountable, plural identities)

1. Sameness, identicalness; the quality or fact of (several specified things) being the same.

   Synonyms: identicalness, identicality, sameness; see also Thesaurus:sameness

   Antonyms: unidenticality, nonidentity; see also Thesaurus:difference

   Coordinate terms: equivalence; fungibility, interchangeability; commensurateness; similarity; resemblance

   • 1664, H[enry] More, chapter X, in Synopsis Prophetica; or, The Second Part of the Modest Enquiry into the Mystery of Iniquity:[…], London: […] James Flesher, for William Morden[…], →OCLC, book I, page 264:

     But whenas a leſſer number of Agreements in each Paralleliſm (provided there were nothing contrary) could not but have been a ſtrong preſumption of the Identity of the Subjects of the Viſions in each Chapter, I mean, That the Two-horned Beaſt and the Whore are one, and the Seven-headed Beaſt in each Chapter the ſame; how fully aſſured muſt we needs be of theſe Identities, the Agreements of theſe two Paralleliſms (thoſe paſſages onely excepted of which I have given ſo fair an account) perfectly exhauſting the whole ſubſtance of each Chapter?

   • 1997, “Hydrothermal Vent Fauna”, in Advances in Marine Biology: The Biogeography of the Oceans, page 111:

     […] suggesting the two are different stages of the same species. The identity of the two species is further suggested by allozyme analysis […]

2. The difference or character that marks off an individual or collective from the rest of the same kind; selfhood; the sense of who something or someone or oneself is, or the recurring characteristics that enable the recognition of such an individual or group by others or themselves.

   Synonyms: individuality; see also Thesaurus:selfhood

   I've been through so many changes, I have no sense of identity.

   This nation has a strong identity.

   • 1904–1907 (date written), James Joyce, “The Dead”, in Dubliners, London: Grant Richards, published June 1914, →OCLC, page 277:

     His own identity was fading out into a grey impalpable world: the solid world itself which these dead had one time reared and lived in was dissolving and dwindling.

   • 2021 July 28, Fausto Cercignani, “On the alleged existence of a vowel /yː/ in early Modern English”, in English Language and Linguistics, volume 26, number 2, Cambridge University Press, →DOI, page 2:

     On the other hand, ME /ɛu/ preserved its identity into the early Modern English period, and the early writers on orthography and pronunciation normally distinguish between lME /iu/ and lME /ɛu/, the latter of which occurs in words with eME /ɛː/ like dew (OE dēaw), few (OE fēawe), hew (OE hēawan), sew (eME ē < ĕ, OE seowian), shrew (OE scrēawa), etc.

3. A name or persona—a mask or appearance one presents to the world—by which one is known.

   This criminal has taken on several identities.

   In this show, the competitor's identity will remain secret until after the vote.

4. (mathematics) An equation which always holds true regardless of the choice of input variables.

   Synonym: identity function

   The equation (x+y)(x−y) = x²−y² is an algebraic identity. It is true regardless of the values of x and y.

5. (algebra, computing) Any function which maps all elements of its domain to themselves.
6. (algebra) An element of an algebraic structure which, when applied to another element under an operation in that structure, yields this second element.

   Zero is the identity for the addition of real numbers.

7. (Australia, New Zealand) A well-known or famous person.

   Synonyms: celebrity, personality

   • 1887 July 19, “Drowned at Williamstown”, in The Age‎^[1], Melbourne:

     The body of a well known old identity named James Conroy […] was found in the water yesterday afternoon…

   • 2013 April 4, “Cricket identities consult lawyers”, in New Zealand Herald:
   • 2016 January 13, “Kings Cross identities arrested in connection with murder”, in The Sydney Morning Herald:

• “identity”, in OneLook Dictionary Search.
• identity in Keywords for Today: A 21st Century Vocabulary, edited by The Keywords Project, Colin MacCabe, Holly Yanacek, 2018.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “identity”, in The Century Dictionary[…], New York, N.Y.: The Century Co., →OCLC.
• “identity”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.