n.
(pl. identities)
- the fact of being who or what a person or thing is.
▸the characteristics determining this.
▸
[
as modifier]
serving to establish the identity of the owner:
an identity card.
- a close similarity or affinity.
- Mathematics
(also identity operation)
a transformation that leaves an object unchanged.
▸
(also identity element)
an element of a set which, if combined with another element, leaves that element unchanged.
- Mathematics an equation expressing the equality of two expressions for all values of the variables, e.g. (x + 1)2 = x2 + 2x + 1.
Etymology
C16: from late L. identitas, from L. idem ‘same’.