'in-group' definitions:

Definition of 'in-group'

From: GCIDE

in-group \in"-group`\, in group \in" group`\n. an exclusive circle of people with a common purpose, interests, or attitudes, especially one that produces feelings of camaraderie, exclusivity, community, and solidarity.
Syn: clique, coterie, ingroup, inner circle, pack, camp. [WordNet 1.5 +PJC]