Subgroup
WordNet
noun
(1) (mathematics) a subset (that is not empty) of a mathematical group
(2) A distinct and often subordinate group within a group
WiktionaryText
Noun
- A group within a larger group; a group whose members are some, but not all, of the members of a larger group.
- A subset H of a group G that is itself a group and has the same binary operation as G.