If you say that someone is temperamental, you are criticizing them for not being calm or quiet by nature, but having moods that change often and suddenly.
双语例句
例：
He is very temperamental and critical.
他喜怒无常，而且吹毛求疵。
2.?（机器、汽车等）性能不稳定的
If you describe something such as a machine or car as temperamental, you mean that it often does not work well.