Bilious is one of several words whose origins trace to the old belief that four bodily humors (black bile, yellow bile, phlegm, and blood) control temperament. Just like phlegmatic ("of a slow and stolid phlegm-driven character"), melancholy ("experiencing dejection associated with black bile"), and sanguine ("of a cheerful, blood-based disposition"), bilious suggests a personality associated with an excess of one of the humors—in this case, yellow bile. Bilious, which first appeared in English in the mid-1500s, derives from the Middle French bilieux, which in turn traces to bilis, Latin for "bile." In the past, bile was also called choler, which gives us choleric, a synonym of bilious.