choleric

This term describes a specific kind of volatility where anger is not just a reaction, but a dominant personality trait. It suggests a hair-trigger temper that flares up quickly and intensely, often over trivial matters.

While "irritable" might imply a general state of annoyance, "choleric" carries a heavier, more aggressive weight. It evokes the image of a person who is perpetually on the edge of an outburst, creating a tense atmosphere for those around them.