The deliberate assumption of another person's identity, usually to gain access to that person's finances or to frame a person for a crime.

(linear algebra) A diagonal matrix all of the diagonal elements of which are equal to 1.

(mathematics) A function whose value is always the same as its independent variable, and for which the codomain equals the domain.

(complex analysis) The equation e^(i𝜋)=-1,!, which unifies diverse fields of mathematics.

(psychology) A crisis of personal identity.

plural of identity theft

A card or badge showing the official identity of the bearer.

plural of identical twin

One of exactly two siblings produced from the splitting of a single zygote.

(philosophy) The principle that, if two objects are indistinguishable from one another with respect to all of their properties, then they are identical.