An Etymological Dictionary of the German Language/Annotated/Fuchs
Fuchs, masculine, ‘fox, light bay horse, cunning person, freshman (univ.)’ from the equivalent Middle High German vuhs, Old High German fuhs, masculine; corresponding to Dutch vos, Anglo-Saxon and English fox; Gothic *faúhs-, masculine (weak substantive), is not found. The s is a masculine suffix, as in Luchs; it is wanting, therefore, in the older feminine form, Old High German foha, Middle High German vohe, feminine, ‘vixen’ (also ‘fox,’ equivalent to Gothic faúhô, feminine, ‘fox,’ Old Icelandic foa, ‘fox’). Old Icelandic fox, neuter, is used only in the figurative sense of ‘deceit.’ The Modern High German feminine form Füchsin corresponds to Anglo-Saxon fyxen, English vixen. Gothic faúhô, feminine, from pre-Teutonic púkâ, makes it appear possible to connect the word phonetically with Modern High German Vogel, Gothic fugls, pre-Teutonic pukló-s, in case Sanscrit puccha, ‘tail, train,’ is of a cognate stem; Fuchs and Vogel, meaning ‘tailed creatures,’ is quite possible. At all events, there is no connection with Latin L. vulpes.