Choler is the one humour whose name became an ordinary English word for anger. To be choleric is to be quick to rage, and the sense has been stable for centuries; bilious carries the same freight, and to say that someone has a jaundiced view of a thing is to speak the humoral theory without knowing it.
The portrait the older writers drew was wider than temper. The choleric complexion was lean rather than full, quick in movement and in speech, bold, ambitious, impatient of contradiction and impatient of delay. It was held to make good soldiers and difficult subordinates. Astrological medicine gave it to Mars, whose traditional qualities are likewise hot and dry, and a chart with Mars strongly placed was read as inclining the native to precisely this set of traits.
Because choler is quick, it was also thought to burn itself out. An excess of a hot humour corrects faster than an excess of a cold one, which is why the choleric person in these accounts is furious and then finished, as against the melancholic person who broods and does not recover. That contrast between a temper that flares and one that settles is the most durable thing in the whole scheme. It survives in ordinary talk about personality long after the fluids it was built on were abandoned by medicine, and it is the reason the four names remain usable when almost nothing else in Galenic physiology does.
Sources On the Affected Parts / On My Own Opinions (Galenic corpus, reference synthesis)Galen; reference synthesis by Wikipedia contributors with Christian AstrologyWilliam Lilly