Petulance is the mood, or the way of behaving, of someone who is impatient and a bit angry in an unreasonable, childish way. It is not deep rage. It is the huffing, the short answers, the “fine, then” when a person does not get what they wanted straight away. Children show it, but adults show it too — a boss, a partner, a customer in a shop — and when we use this word we are usually criticising them. We are saying they are acting younger than they are. You will hear it more in writing and careful speech than in casual chat. A single sharp moment can be petulance; a person who lives in that mood is showing a character trait, not just a bad afternoon.

任性、耍脾氣