The four elemental qualities that make up the human body, historically comprising blood, phlegm, choler, and melancholy. When they are in balance, health results; imbalance creates sickness.

(Also spelled Humours.) Mentions of the humors refer to the ancient Greek theory that a person's health and personality were determined by the balance of four basic fluids in the body: blood, phlegm, yellow bile, and black bile. A dominance of any fluid would cause extremes in behavior. An excess of blood created a sanguine person who was joyful, aggressive, and passionate; a phlegmatic person was shy, fearful, and sluggish; too much yellow bile led to a choleric temperament characterized by impatience, anger, bitterness, and stubbornness; and excessive black bile created melancholy, a state of laziness, gluttony, and lack of motivation. Literary treatment of the humors is exemplified by several character s in Ben Jonson's play Every Man in His Humour and Every Man out of His Humour.