Mistake  —n. 1 incorrect idea or opinion; thing incorrectly done or thought. 2 error of judgement. —v. (-king; past mistook; past part. Mistaken) 1 misunderstand the meaning of. 2 (foll. By for) wrongly take or identify (mistook me for you). 3 choose wrongly (mistake one's vocation). [old norse: related to *mis-1, *take]