Sanguine is a formal word that today almost always describes someone who is confident and hopeful, or something that shows confidence and hopefulness. Sanguine can also describe something that is bloodred in color, something involving or relating to bloodshed, or a person’s reddish complexion.

// The young group of entrepreneurs is sanguine about the future of their business.

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“[David] Corenswet is remarkably sanguine about a film that has been the subject of immense scrutiny. The trailer is the most watched in the history of either DC or Warner Bros. Though he may not want the burden of Superman’s success or failure on his, yes, broad shoulders, it will land there anyway.” — Eliana Dockterman, Time, 1 Apr. 2025

If you’re the sort of cheery, confident soul who always looks on the bright side no matter what happens, you may be described as sanguine. Sanguine traces back to the Latin noun sanguis, meaning “blood,” and over the centuries the word has had meanings ranging from “bloodthirsty” to “bloodred,” among other things in that (ahem) vein, so how did it also come to mean “hopeful”? During the Middle Ages, health and temperament were believed to be governed by the balance of different liquids, or humors, in one’s body: phlegm, black bile, yellow bile, and blood. Those lucky people who were governed by blood were strong, confident, and even had a healthy reddish glow (all that blood, you know)—they were, in a word, sanguine. In time, the physiological theory behind the humors was displaced by scientific medicine, but the word sanguine is still commonly used to describe those who are cheerfully confident.