From Proto-Germanic *wulfaz, from Proto-Indo-European *wĺ̥kʷos. Germanic cognates include Old Frisian wolf, Old Saxon wulf, Dutch wolf. Old High German wolf (German Wolf), Old Norse úlfr (Swedish ulv), Gothic 𐍅𐌿𐌻𐍆𐍃 (wulfs). The Indo-European root is also the source of Avestan vəhrka-, Lithuanian vilkas, Old Church Slavonic влькъ (vlĭkŭ) (Russian волк (volk)). Ancient Greek λύκος (lúkos) and Latin lupus also probably from the same root, either internally borrowed or with metathesis because of a wolf taboo.