Cliques

noun

1. A small, exclusive group of individuals, usually according to lifestyle or social status; a cabal.

   "This school used to be really friendly, but now everyone keeps to their own cliques."

2. A subgraph isomorphic to a complete graph.

   "The problem of finding the largest clique in an arbitrary graph is NP-complete."

3. A group of related web sites that link to each other, like a webring but with exclusive membership determined by the clique owner.