sanguineous

Sanguineous isn't the only English adjective to come from "sanguis," the Latin word for "blood." "Sanguine," for one, has been with us since the 14th century. Nowadays, it usually means "confident" or "optimistic," but it can also mean "ruddy." (The "optimistic" sense stems from the medieval belief that a healthy red complexion denoted a courageous and hopeful temperament.) "Sanguineous" first appeared in the 16th century as a synonym of the "ruddy" sense of "sanguine," but now it's more often used in medical or scientific references to blood. It shares another sense - "bloodthirsty" or "involving bloodshed" - with "sanguinary," yet another "sanguis" descendant."