temperamental
adjective
1. relating to or caused by temperament
- temperamental indifference to neatness
- temperamental peculiarities
2. subject to sharply varying moods
- a temperamental opera singer
Similar word(s): emotional, moody
3. likely to perform unpredictably
- a temperamental motor; sometimes it would start and sometimes it wouldn't
- that beautiful but temperamental instrument the flute
Similar word(s): undependable, unreliable, erratic