An Etymological Dictionary of the German Language/wo

by Friedrich Kluge

wo, adv., ‘where,’ from MidHG. and OHG. wâ for older wâr, ‘where’; comp. OSax. hwâr, Du. waar, AS. hwœ̂r, E. where, and the equiv. Goth. hwar. A local adv. from the old interr. pron. hwa-, from Aryan ko-; comp. Sans. kárki, ‘when.’ See wer and warum.