Adjective: temperamental ,tem-pru'men-tul
- Relating to or caused by temperament
"temperamental indifference to neatness"; "temperamental peculiarities"
- Subject to sharply varying moods
"a temperamental opera singer";
- moody
- Likely to perform unpredictably
"a temperamental motor: sometimes it would start and sometimes it wouldn't"; "that beautiful but temperamental instrument the flute";
- erratic
See also: emotional, flakey [informal], flaky [informal], undependable, unreliable
Encyclopedia: Temperamental