temperamental adjective definition in Excitement topic from the Oxford Advanced Learner's Dictionary

temperamental

 adjective: Excitement topic
(usually disapproving) having a tendency to become angry, excited or upset easily, and to behave in an unreasonable way You never know what to expect with her. She's so temperamental. (figurative) The printer's being temperamental this morning. He’s a temperamental player (= he plays well or badly according to his mood).