noun
short-tempered person; irritable person
Colloquial, often used for children or in a teasing way. Describes someone who gets angry easily.
うちの弟は怒りん坊で、すぐに怒る。
My little brother is short-tempered and gets angry quickly.
あの子は怒りん坊だから、からかわないほう
That kid is irritable, so you'd better not tease him.