late 14c., altered from or re-formed to replace unwitand, from Old English unwitende "ignorant," from un- (1) "not" + witting (adj.); see -ing (2). Similar formation in Old High German unwizzanti, German unwissend, Old Norse uvitandi, Gothic unwitands. Rare after c. 1600; revived c. 1800. Related: Unwittingly.