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)).
coil v.
1610s, "to wind, gather into rings one above the other" (trans.), from French coillir "to gather, pick," from Latin colligere "to gather together" from assimilated form of com "together" (see co-) + legere "to gather," from PIE root *leg- (1) "to collect, gather." Intransitive sense "to form rings or spirals" is by 1798. Related: Coiled; coiling.