An Etymological Dictionary of the German Language/geschwind
geschwind, adj. and adv., ‘swift(ly), rapid(ly), quick(ly),’ from geswinde, adj. and adv., ‘quick(ly), vehement(ly)'; in earlier ModHG. schwinde, MidHG. swinde (swint), ‘powerful, strong, quick.’ In OHG. the adj. is wanting (yet the proper names Amalswind and Adalswind are recorded). The prim. meaning is ‘strong’; the development of meaning to ‘quick’ is similar to that of bald; Goth. swinþs, ‘strong, powerful, healthy,’ OIc. svinnr, ‘intelligent,’ AS. swið, ‘strong, violent,’ show various aspects of the primary meaning. The origin of the cognates is obscure; its relation to gesund is dubious.