Translate identity | into French | into German | into Italian | into Spanish Definition of identity
noun (plural identities)
1the 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 modifier] chiefly
British (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
2a close similarity or affinity:the initiative created an identity between the city and the suburbs
3 Mathematics (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 Mathematics 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.
