identitynoun/aɪˈdɛntɪti/

• 1

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

  • Benjamin Franklin established the identity of electricity and lightning.
  • 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?
• 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.

  • I've been through so many changes, I have no sense of identity.
  • This nation has a strong identity.
• 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

  mathematicssciencesAn equation which always holds true regardless of the choice of input variables.

  • The equation (x+y)(x−y) = x²−y² is an algebraic identity. It is true regardless of the values of x and y.
• 5

  algebracomputingengineeringAny function which maps all elements of its domain to themselves.

• 6

  algebramathematicssciencesAn 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

  A well-known or famous person.

  • The body of a well known old identity named James Conroy […] was found in the water yesterday afternoon…
  • The 79-year-old man who died days after he was struck by a car in Westport was a local identity who was well known for his walks around town.