1. Cheerfully confident; optimistic. 2. Of the color of blood; red
In her excellent novel Jonathan Strange & Mr Norrell, Susanna Clarke must have used this word at least 10 times, to refer to the cheerful confidence, not the color. I never see the word used in the color sense, even though that’s the meaning that both the American Heritage and Merriam-Webster’s put first. Oh well. Isn’t it odd that a word with blood at its root could come to mean cheerful or hopeful? Well, back in the day—and I mean way, way, way back in the day—people used to think that the body was composed of four major fluids, or humors, and that a predominance of the blood humor was a sign of good health or something like that. So that’s where it comes from. If you want to learn more about the humors, including my favorite, phlegm, check out the word history of sanguine in the American Heritage Dicationary.