(medicine) The basic system of categorizing blood by antigen type.

A group of musicians who regularly perform together.

Alternative form of abelian group

(astronomy) A group of galaxies that hold together gravitationally.

(group theory) A group obtained from a larger group by aggregating elements via an equivalence relation that preserves group structure.

(group theory) The unique group (up to isomorphism) consisting of a single element (which is the identity element).

(group theory) A group which has no normal subgroups apart from the trivial group and itself.

(group theory) a group of symmetries of a regular polygon

(group theory) a group of even permutations of a finite set

(algebra, group theory) A group whose elements are permutations (self-bijections) of a given set and whose group operation is function composition.