also: むか
expression
suddenly angry; flare up in anger
Mimetic expression describing a sudden, brief flash of anger or irritation. Often used in casual, colloquial contexts.
See also: むかっと
彼の一言にムカッときた。
I got suddenly angry at his remark.
ムカッとしたけど、すぐに落ち着いた。
I flared up for a moment, but quickly calmed down.
Hiragana spelling, also used.
むかっと is a more standard adverbial form, while ムカッ is a more colloquial, standalone mimetic expression.
Mimetic word; the sound ムカッ imitates the sudden surge of anger. The exact origin is uncertain.