What is the X in X-mas?
1711, "a party of persons; a small set, especially one associating for exclusivity," from obsolete French clique, originally (14c.) "a sharp noise," also "latch, bolt of a door," from Old French cliquer "click, clatter, crackle, clink," 13c., echoic. Apparently this word was at one time treated in French as the equivalent of claque (q.v.) and partook of that word's theatrical sense.