clique
n. countablen. a small group of people who spend a lot of time together and do not like to let others join. It often feels unfriendly to people on the outside.
n. a small, exclusive group of friends or associates, often perceived as snobbish or exclusionary. Frequently carries a negative connotation regarding social dynamics.
The popular kids formed a clique and ignored everyone else.
In high school, it can be difficult to make new friends if every social group has already formed a tight clique.
The office environment became toxic as a small clique of senior managers began making important decisions during private lunches, effectively bypassing the official departmental channels.
Borrowed from French clique, ultimately of imitative origin. Influenced by "claque", though this may have happened in French rather than in English.
Often used with the verbs 'form', 'join', or 'break into'.