temperamental

adjective

1. 1

   likely to perform unpredictably

   erratic winds are the bane of a sailor

   a temperamental motor; sometimes it would start and sometimes it wouldn't

2. 2

   subject to sharply varying moods

   a temperamental opera singer

3. 3

   relating to or caused by temperament

   temperamental indifference to neatness

   temperamental peculiarities