1. The collective aspect of the set of characteristics by which a thing is definitively recognizable or known: "If the broadcast group is the financial guts of the company, the news division is its public identity" (Bill Powell).
2. The set of behavioral or personal characteristics by which an individual is recognizable as a member of a group.
3. The quality or condition of being the same as something else.
4. The distinct personality of an individual regarded as a persisting entity; individuality.
5. Information, such as an identification number, used to establish or prove a person's individuality, as in providing access to a credit account.
6. Mathematics.
   1. An equation that is satisfied by any number that replaces the letter for which the equation is defined.
   2. Identity element.

[French identité, from Old French identite, from Late Latin identitās, from Latin idem, the same (influenced by Late Latin essentitās, being,identidem, repeatedly), from id, it.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.