Bilious: The adjective for bile, bilious has three meanings. It means of or relating to bile. By extension, bilious means suffering from liver dysfunction (and especially excessive secretion of bile). And, further by extension, it is indicative of a peevish ill-natured disposition.

The word "bilious" goes back to the old belief that there were four bodily humors (black bile, yellow bile, phlegm, and blood) and these four humors determined a person's temperament. "Bilious" was the personality type associated with an excess of yellow bile. The word "bilious" derives from the French "bilieux," which in turn came from "bilis," the Latin term for "bile."