köken: Contracted form of weder (“again”), from Middle Dutch wēder, from Old Dutch wither, from Proto-West Germanic *wiþr, from Proto-Germanic *wiþrą (“against”), from Proto-Indo-European *wit(e)rom (“more apart”), from *wí (“separation”).
aile: al weer, alweer, heen en weer, over en weer, wederantwoord, wederdienst, wederdoper, wedergeboorte, wederhelft, wederom
köken: From Proto-Slavic *vьlkolakъ. First attested in the 16th century.
Etimoloji
Inherited from Middle French garou, from Old French garoul, garval, garvalf, garwaf, garwall (Marie de France, c. 1175, Old Northern French), guarou, guaroul, wareu, wareul, warou (“werewolf”), from Frankish *werawulf. OED suggests the French being from Old Norse vargulfr, which however occurs only in the translation of Marie's lay of Bisclavret. In sense 2, back-formation from loup-garou…