An Etymological Dictionary of the German Language/auch

by Friedrich Kluge

auch, adv. and conj., ‘also, likewise,’ from MidHG. ouch, OHG. ouh, ‘and, also, but.’ It corresponds to OSax. ôk, Du. ook; OFries. âk, AS. eác, E. eke, OIc. auk, ‘besides,’ Dan. og, ‘and, also, but,’ Sw. och, Ic. ok; Goth. auk, ‘then, but’; an adv. common to Teut. Some refer this auk to the Teut. root auk (Aryan aug), ‘to increase,’ whence OHG. ouhhôn, ‘to add,’ OSax. òkian, AS. ŷcan, OIc. auka, Goth. aukan, ‘to increase,’ are derived (Lat. augere, aug-ustus, Sans. ugrás, ‘powerful,’ ôjas, ‘strength,’ are allied to them); comp. AS. tô-eácan, ‘moreover, also.’ Others trace Teut. auk to a compound of two Aryan particles, au and ge (Gr. αὖ, γε).