bilious

Bilious is an English adjective with several related senses. It originally derives from the Latin bilis, bile, and entered English via Old French bilieux. The primary sense is anatomical: pertaining to bile or the biliary system, or indicating a condition involving bile production or flow. In medical contexts, bilious may describe symptoms suggesting bile-related irritation, such as bilious vomiting or biliousness, though modern medical language prefers more precise terms.

A second sense arises from the longstanding belief in the four humors: a bilious temperament or bilious person is irritable, irascible, or spiteful; this usage is largely literary and archaic today but appears in historical and poetic writing. Relatedly, bilious can describe a yellow-green coloration reminiscent of bile, or describe something with a yellow-green hue.

In general usage outside medicine, bilious is usually applied to color or mood rather than clinical diagnosis. It may describe a greenish tint in objects or surfaces, or figuratively denote a bilious mood conjuring irritability or ill temper. The term remains in use in dictionaries as both a medical descriptor and a literary one, but it is less frequent in everyday clinical practice, having largely been supplanted by more precise terminology.

See also: bile, biliary system, choleric temperament, yellow bile.