An Etymological Dictionary of the German Language/wissen
wissen, vb., ‘to know, beware of,’ from the equiv. MidHG. wiȥȥen, OHG. wiȥȥan; a common Teut., and more remotely a primit. Aryan pret. present. Comp. Goth. wait, ‘I know,’ AS. wât, E. wot, OSax. wêt, OHG. and MidHG. weiȥ. Based on pre-Teut. woid, wid, in Sans. vêda, ‘I know,’ Gr. οἶδα, OSlov. vĕděti, ‘to know.’ This primit. unreduplicated perfect is based on a root wid, which in the Aryan languages means lit. ‘to find,’ then ‘to see, recognise’; comp. Sans. vid, ‘to find,’ Gr. ἰδεῖν, Lat. videre, ‘to see,’ Goth. witan, ‘to observe.’ In Ger. comp. gewiß, verweisen, weissagen, Witz.