The element of a set of numbers that when combined with another number under a particular binary operation leaves the second number unchanged. For example, 0 is the identity element under addition for the real numbers, since for any real number a, a + 0 = a, and 1 is the identity element under multiplication for the real numbers, since a × 1 = a.
noun, Mathematics. 1. (def 9d).
noun, Mathematics. 1. a matrix that has 1 in each position on the main diagonal and 0 in all other positions.
noun, (used with a singular or plural verb) 1. political activity or movements based on or catering to the cultural, ethnic, gender, racial, religious, or social interests that characterize a group identity.
noun 1. the symbol (≡), designating identity, not equality.