- sanguine
- early 14c., "type of red cloth," from Old French sanguin (fem. sanguine), from Latin sanguineus "of blood," also "bloody, bloodthirsty," from sanguis (genitive sanguinis) "blood" (see sanguinary). Meaning "blood-red" is recorded from late 14c. Meaning "cheerful, hopeful, confident" first attested c.1500, because these qualities were thought in medieval physiology to spring from an excess of blood as one of the four humors.