An Etymological Dictionary of the German Language/Annotated/Wiesel
Wiesel, masculine and neuter, ‘weasel,’ from the equivalent Middle High German wisel, wisele, Old High German wisala, feminine; corresponding to Dutch wezel, wezeltje, Anglo-Saxon wësle (weosulœ), English weasel, Danish väsel. It is frequently regarded as a derivative of Wiese, linking it with the place where the animal is usually found; others, on account of the keen scent of the animal, connect its name with Latin virus, ‘poison’ (root wī̆s, see verwesen). Both derivations are very uncertain.