prefix of reversal, deprivation, or removal (as in unhand, undo, unbutton), Old English on-, un-, from Proto-Germanic *andi- (source also of Old Saxon ant-, Old Norse and-, Dutch ont-, Old High German ant-, German ent-, Gothic and- "against"), from PIE *anti "facing opposite, near, in front of, before, against" (from PIE root *ant- "front, forehead," with derivatives meaning "in front of, before").
More or less confused with un- (1) through similarity in the notions of "negation" and "reversal;" an adjective such as unlocked might represent "not locked" (un- (1)) or the past tense of unlock (un- (2)).
hitch v.
mid-15c., probably from Middle English icchen "to move as with jerks or pauses; to stir" (c. 1200), a word of unknown origin. The connection with icchen might be in notion of "hitching up" pants or boots with a jerking motion. Sense of "become fastened," especially by a hook, first recorded 1570s, originally nautical. Meaning "to marry" is from 1844 (to hitch horses together "get along well," especially of married couples, is from 1837, American English). Short for hitchhike (v.) by 1931. Related: Hitched; hitching. To (figuratively) hitch (one's) wagon to a star is by 1862.