(organic chemistry) Any chemical entity that is temporarily reacted with a functional group so as to protect it from a subsequent reaction

(group theory) A group that has a presentation without relators; equivalently, a free product of some number of copies of ℤ.

(computing) A set of users grouped together on a system for administrative purposes. / (computing) A community of users of a particular machine, operating system, etc.

(chemistry) An atom or group that is detached from the rest of a molecule during a reaction.

(mathematics) Any discrete group of isometries of the hyperbolic plane.

(marketing) The primary group of people that something, usually an advertising campaign, is designed to appeal to.

A front organization that appears to be an independent voluntary association or charitable organization.

Any of several small groups of people, at a conference etc., who concentrate effort on a part of the main topic.

(algebra) Given ring R with identity not equal to zero, and group G=g_1,g_2,...,g_n, the group ring RG has elements of the form a_1g_1+a_2g_2+...+a_ng_n (where a_i isin R) such that the sum of a_1g_1+a_2g_2+...+a_ng_n and b_1g_1+b_2g_2+...+b_ng_n is (a_1+b_1)g_1+(a_2+b_2)g_2+...+(a_n+b_n)g_n and the product is ∑ₖ₌₁ⁿ(∑_(g_ig_j=g_k)a_ib_j)g_k.

(group theory) Any (often, but not necessarily, abelian) group whose binary operation is called addition.