"accustomed," Old English wunod, past participle of wunian "to dwell, be accustomed," from Proto-Germanic *wun- "to be content, to rejoice" (cf. Old Saxon wunon, Old Frisian wonia "to dwell, remain, be used to," Old High German wonen, German wohnen "to dwell;" related to Old English winnan, gewinnan "to win" (see win) and to wean. The noun meaning "habitual usage, custom" is attested from c.1300.
contraction of will not, first recorded mid-15c. as wynnot, later wonnot (1580s) before the modern form emerged 1660s. See will.