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.

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

"a harbor on the sea; a city or town on such a harbor," 1590s, from sea + port (n.1).

"to rest or place on or as on a pillow," 1620s, from pillow (n.). Related: Pillowed; pillowing.

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).

1630s, from Japanese kimono, literally "a thing put on," from ki "wear, put on" + mono "thing."

"on which," c. 1200, from where (in the sense of "in which position or circumstances") + on (adv.).

"on the contrary, on the other hand," mid-15c.; see contrary + wise (n.).