noun
venting one's anger; retaliation; revenge
Refers to taking out one's anger or frustration on someone or something, often in a petty or indirect way, rather than a calculated act of revenge.
彼は上司に叱られた腹いせに、部下に当たった。
He took out his anger on his subordinate after being scolded by his boss.
ただの腹いせでそんなことを言うのはやめなさい。
Stop saying things like that just to vent your anger.
Compound of 腹 (hara, 'belly', metaphorically the seat of emotions) and いせ, the nominalized form of 癒す (iyasu, 'to heal, soothe'). Literally 'soothing one's belly', it came to mean venting one's anger to feel better.