identity

identity in philosophy, problem of distinguishing sameness from change, or unity from diversity; primarily examined in connection with personal identity, universals, and the law of identity in logic. In personal identity the concern has been to determine whether anything in the body or mind remains constant; philosophers have reached no general agreement on this point. The term identity has also become increasingly important in modern psychology, largely through the work of Erik Erikson. He has used the term to designate a sense of self that develops in the course of a man's life and that both relates him to and sets him apart from his social milieu. The terms "identity crisis" and "identity confusion," introduced by Erikson, have gained a wide usage, which often varies from their intended technical sense.

identity quality of being the same. XVI. — late L. identitās, f. L. idem same.
So identic(al), identify XVII. — medL.

i·den·ti·ty / īˈdentitē/ • n. (pl. -ties) 1. the fact of being who or what a person or thing is: he knows the identity of the bombers | she believes she is the victim of mistaken identity. ∎  the characteristics determining this: attempts to define a distinct Canadian identity. ∎  [as adj.] chiefly Brit. (of an object) serving to establish who the holder, owner, or wearer is by bearing their name and often other details such as a signature or photograph: an identity card. 2. a close similarity or affinity: the initiative created an identity between the city and the suburbs. 3. Math. (also identity operation) a transformation that leaves an object unchanged. ∎  (also identity element) an element of a set that, if combined with another element by a specified binary operation, leaves that element unchanged. 4. Math. the equality of two expressions for all values of the quantities expressed by letters, or an equation expressing this, e.g., (x + 1)² = x² + 2x + 1. ORIGIN: late 16th cent. (in the sense ‘quality of being identical’): from late Latin identitas, from Latin idem ‘same.’