Definition of: sanguine

(sang′gwin) adjective
1. Of buoyant disposition; hopeful; confident; originally, having a temperament supposed to be due to active blood.
2. Having the color of blood; of, like, or full of blood.
3. Obs. Bloodthirsty; sanguinary. [<OF sanguin <L sanguineus <sanguis, sanguinis blood]
—san′guine·ly adverb
—san′guine.ness n. Synonyms: animated, ardent, buoyant, confident, enthusiastic, hopeful. Sanguine, from the same root as sanguinary, came to denote full–blooded or plethoric, hence, ardent, confident, hopeful, because these qualities were supposed to be associated with fullness of blood. For the rare use of sanguine in direct literal sense, see synonyms under SANGUINARY.