I
(Latin; " fluid ")
In early Western physiological theory, one of the four body fluids thought to determine a person's temperament and features.
As hypothesized by Galen , the four cardinal humours were blood, phlegm, choler (yellow bile), and melancholy (black bile). The variant mixture of these humours in each person determined his "complexion" or temperament and his mental and physical qualities. The ideal person had the perfectly proportioned mixture of the four fluids; a disproportionate amount of one humour created a personality dominated by one set of related emotions (e.g., a choleric man was easily angered, proud, ambitious, and vengeful).
II
[c mediumvioletred] (as used in expressions)
black humour
cerebrospinal fluid
{{link=fluid mechanics">fluid mechanics