An Etymological Dictionary of Astronomy and Astrophysics

Any of several carnivores of the dog family, especially those of the genus Vulpes, smaller than wolves, having a pointed, slightly upturned muzzle, erect ears, and a long, bushy tail (Dictionary.com).

Etymology (EN): M.E., from O.E. fox “a fox;” cognate with O.Saxon vohs, M.Du. vos, O.H.G. fuhs, Ger. Fuchs, from Proto-Germanic *fuh-, from PIE *puk- “tail;” cf. Skt. puccha- “tail,” Toch. B päkā- “tail.”

Etymology (PE): Rubâh, from Mid.Pers. rôbâh (Sogd. ropas), Av. raopi- “fox.” This Iranian word was borrowed into Nordic languages as Old Norse rew, Icelandic refur, Faroese revur, Swedish räv, Danish ræv, Finnish repo. The transmission would have taken place through Sarmatian or Alanic intermediaries (cf. Ossetic ruvas / robas “fox”).