late 14c., "device to hold a latch of a door," also "a trap;" also "a fishing vessel," from catch (v.). The meaning "action of catching" is attested from 1570s. The meaning "that which is caught or worth catching" (later especially of spouses) is from 1590s. The sense of "hidden cost, qualification, etc.; something by which the unwary may be entrapped" is slang first attested 1855 in writings of P.T. Barnum.

1711, "an exclusive party of persons; a small set, especially one associating to arrogate power or privilege," from obsolete French clique, which meant 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.

Old English clingan "hold fast, adhere closely; congeal, shrivel" (strong verb, past tense clang, past participle clungen), from Proto-Germanic *klingg- (source also of Danish klynge "to cluster;" Old High German klinga "narrow gorge;" Old Norse klengjask "press onward;" Danish klinke, Dutch klinken "to clench;" German Klinke "latch").

The main sense shifted in Middle English to "adhere to" (something else), "stick together." Of persons in embrace, c. 1600. Figuratively (to hopes, outmoded ideas, etc.), from 1580s. Of clothes from 1792. Related: Clung; clinging.

c. 1200, afote, "on foot, walking, not on horseback," contraction of prepositional phrase on fotum; see a- (1) "on" + foot (n.). Meaning "astir, on the move" is from 1520s; figurative sense of "in active operation" is from 1601 ("Julius Caesar").

late 14c., "on fire," from a "on" (see a- (1)) + blaze (n.).

also on-going, "progressing, proceeding, not intermitting," 1877, from on + going.

"with one leg on each side," 1660s, from a- (1) "on" + stride (n.).

"on fire, ablaze," 1550s, from a- (1) "on" + flame (n.). Figurative use by 1856.

plural of tenterhook (late 15c.), "one of the hooks that holds cloth on a tenter," from tenter (q.v.) + hook (n.). The figurative phrase on tenterhooks "in painful suspense" is from 1748; earlier to be on tenters (1530s).

slang for "quiet," in phrase on the q.t., attested from 1874. Phrase on the quiet appears from 1847.