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

Having to do with group theory.

plural of group theoretician

(rare) A group theorist.

Having to do with group theory.

The subgroup of a specified group generated by the larger group's commutators.

(in an experiment) The group of test subjects left untreated or unexposed to some procedure and then compared with treated subjects in order to validate the results of the test.

(Internet) A group of people who meet and chat online, especially in a chat room

(Internet) An online discussion group.

The behaviour of a group of people governed by their mutual interaction. / The study of this behaviour.