Noun
Brauer group (plural Brauer groups)
English Wikipedia has an article on:Brauer groupWikipedia
(mathematics) For a field K, an abelian group whose elements are Morita equivalence classes of central simple algebras over K, with addition given by the tensor product of algebras.
Explicitly, the Brauer group of the reals consists of two classes, represented by the reals and the quaternions, where the Brauer group is the set of all CSAs, up to equivalence relation of one CSA being a matrix ring over another. Source: Internet