An Etymological Dictionary of the German Language/Werwolf
Werwolf, m., ‘werewolf,’ from the equiv. MidHG. wërwolf (not recorded in OHG.). It is undoubtedly based on an OTeut. word; comp. AS. wërewulf, E. werewolf. From the AS. word is derived MidLat. guerulfus, OFr. garou, whence by tautology ModFr. loup-garou, ‘werewolf.’ The presupposed OTeut. werowulfo- means lit. ‘man-wolf,’ i.e., a man who roams about in the form of a wolf (Gr. λυκάνθρωπος). The first component is OHG., OSax., and AS. wër (Goth. waír), m., ‘man,’ primit. cognate with Lat. vir, Sans. vîras, ‘man.’