noun
irritation; annoyance; frustration
A feeling of being irritated or annoyed, often due to a specific trigger.
彼の態度に苛立ちを感じた。
I felt irritation at his attitude.
苛立ちを抑えられなかった。
I couldn't suppress my frustration.
Noun form of the verb 苛立つ (いらだつ), from 苛 (いら, 'thorn, irritation') + 立つ (たつ, 'to stand, rise').