An Etymological Dictionary of the German Language/Annotated/Widder
Widder, masculine, ‘ram,’ from Middle High German wider, Old High German widar, masculine; corresponding to Gothic wiþrus, masculine (ram? lamb?), Anglo-Saxon wëðer, English wether, Dutch weder, ‘ram, wether.’ Teutonic weþru-, from pre-Teutonic wétru-, is primitively allied to Latin vitulus, ‘calf,’ Sanscrit vatsá, ‘calf, young animal,’ which are derived from Aryan wet-,‘year’; compare Latin vetus, ‘aged,’ Greek ἔτος, Sanscrit vatsara, ‘year.’ Hence Widder means literally ‘young animal, yearling.’