One of the mysteries of the English language finally explained.
The theory that health, disease, and temperament are determined by the four humours of the body. Also (more generally): the theory that all disease can be ascribed to the state of the body fluids, especially the blood.
Early 19th century. From humoral + -ism. Compare slightly earlier humorism, and also earlier humoralist.
In this article we explore how to impress employers with a spot-on CV.