Formal:
* Irascible: This word emphasizes a tendency towards anger, particularly sudden and unpredictable outbursts.
* Irritable: This implies a general state of being easily annoyed or angered.
* Short-tempered: This describes someone who gets angry quickly and easily.
* Quick-tempered: Similar to short-tempered, but with a focus on the speed with which they become angry.
Informal:
* Hot-headed: This emphasizes impulsiveness and passion, often leading to anger.
* Touchy: This means easily offended or upset, often by seemingly insignificant things.
* Easily provoked: This describes someone who is easily angered by external stimuli.
Other options:
* Volatile: This suggests an unstable emotional state, prone to sudden changes, including anger.
* Explosive: This is a strong term, suggesting a powerful and sudden release of anger.
The best word to use will depend on the specific context and the desired level of formality.