sanguine

Etymology

From Middle English sanguine, from Old French sanguin, ultimately from Latin sanguineus (“of blood”), from sanguis (“blood”) (of uncertain origin, but probably from Proto-Indo-European *h₁sh₂-én-, from *h₁ésh₂r̥ (“blood”), with an obscure suffix such as *-ǵʰ- (related to body parts)) + -inus + -eus. The obsolete medical sense is in reference to the humour (blood) which ancient Hippocratic and later Galenic medicine associated with cheerfulness, optimism, confidence, liveliness, and spiritedness. Doublet of sanguineous.