Refers to a person's disposition or irritability. Often used in compounds like 癇に障る (to get on one's nerves) or 癇が強い (short-tempered).
The way he said it got on my nerves.
That child has a strong temper, so it's hard to handle.
temper; tantrum; fit of anger
eclampsia
irritability; peevishness; hot temper
short temper; irritability
Jacksonian epilepsy
The kanji 癇 is composed of 疒 (sickness) and 間 (interval), suggesting a pathological condition related to the mind or nerves. The exact historical derivation is uncertain.