noun
A sudden, visceral anger, often described as rising in the belly. Typically used in the expressions むかっ腹が立つ (to get angry) or むかっ腹を立てる (to become angry).
彼の一言でむかっ腹が立った。
That one remark of his made my blood boil.
むかっ腹を立てて、つい怒鳴ってしまった。
I got so angry I ended up yelling.
Kanji spelling using 向かっ, but the kana form むかっ腹 is far more common.
The word is a compound of the mimetic element むかっ (suggesting a sudden surge of emotion) and 腹 (belly), reflecting the Japanese idiom of the belly as the seat of anger. The exact origin of むかっ is uncertain.