A normal functioning fluid or semifluid of the body (as the blood, lymph or bile) especially of vertebrates.
A secretion that is itself an excitant of activity (as certain hormones).
A fluid in the body.
An archaic term once used for a theory regarding the causation of disease as due to an improper mixture in the body of blood, bile, phlegm and black bile. The term remains for the description of some body fluids, such as the aqueous and vitreous humours of the eye.
The term “humour” is used to describe any fluid or gel-like substance found within the body. Most often, it refers to the aqueous humour and vitreous humour present in the eye.