unbind v.

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)).

Old English bindan "to tie up with bonds" (literally and figuratively), also "to make captive; to cover with dressings and bandages" (class III strong verb; past tense band, past participle bunden), from Proto-Germanic *bindanan (source also of Old Saxon bindan, Old Norse and Old Frisian binda, Old High German binten "to bind," German binden, Gothic bindan), from PIE root *bhendh- "to bind." Of books, from c. 1400. Intransitive sense of "stick together, cohere" is from 1670s.