mid-14c., "relax;" late 14c., "to set free," from un- (2), used here emphatically, + loose (v.). Old English had unliesan "unloose, set free." Related: Unloosed; unloosing.
Entries linking to unloose
un- 2
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)).
loose v.
c. 1200, lousen, "to set free, turn loose," also "undo, untie, unfasten," from loose (adj.). Of arrows from c. 1400. Related: Loosed; loosing.