Other forms: coteries
Have you noticed how so many of the best TV shows concentrate on a group of friends who seem to mesh together perfectly, to the exclusion of all others? This, then, is a coterie, an exclusive group with common interests.
The modern spelling and meaning of coterie developed in the 18th century from a French word rooted in the feudal system. When the farmers working the land of a feudal lord established an organization, they were called cotiers, or "tenants of a cote" (think "cottage"), and that idea of a select group led to the word coterie. There's just something so French about the idea of exclusivity, isn't there?