Function: noun
Date: circa 1889
: an algebraic system that consists of a set closed under two binary operations and that can be described by any of various systems of postulates all of which can be deduced from the postulates that each operation is commutative, that each operation is distributive over the other, that an identity element exists for each operation, and that for every element in the set there exists another element which when combined with the first under either one of the operations yields the identity element of the other operation