An Etymological Dictionary of the German Language/Annotated/greis
greis, adjective, ‘grizzled, hoary, aged,’ from the equivalent Middle High German grîs, Old High German grîs (grîsil); compare Old Saxon grîs, ‘hoary’; allied to Greis from Middle High German grîse, ‘old man.’ From this Old German word, unknown to the other Teutonic dialects and obscure in its origin, are derived the Romance cognates, Italian griso, grigio, French gris, ‘grey’ (Italian grigio, from Gothic *greisja-?. Compare Middle Latin griseus, ‘grey’).