"exclusive set or circle of persons who are in the habit of meeting and socializing, a clique," 1738, from French coterie "circle of acquaintances," originally an organization of peasants holding land from a feudal lord (14c.), from cotier "tenant of a cote" (see cottage).
"small village" (Scottish and Irish), early 15c., from Gaelic clach (plural clachan) "stone," originally perhaps "a stone circle."
late 14c., in geometry, "chord of a circle or sphere which passes through its center; the length of a diameter," from Old French diametre, from Latin diametrus, from Greek diametros (gramme) "diagonal of a circle," from dia "across, through" (see dia-) + metron "a measure" (from PIE root *me- (2) "to measure").
before a vowel, cycl-, word-forming element in technical terms meaning "circle, ring, rotation," from Latinized form of Greek kyklos "circle, wheel, ring" (from PIE root *kwel- (1) "revolve, move round"). In organic chemistry it is used in forming chemical names of cyclic compounds.