temperamental
1. [ adjective ] subject to sharply varying moods
Synonyms: moody
Examples:

"a temperamental opera singer"

Related terms: emotional
2. [ adjective ] relating to or caused by temperament
Examples:

"temperamental indifference to neatness" "temperamental peculiarities"

Related terms: disposition
3. [ adjective ] likely to perform unpredictably
Synonyms: erratic
Examples:

"erratic winds are the bane of a sailor" "a temperamental motor sometimes it would start and sometimes it wouldn't" "that beautiful but temperamental instrument the flute"- Osbert Lancaster

Related terms: unreliable
Similar spelling:   temperamentally
  temperament
  temperately
  temperance
  temperature
  ten_percent
  temperateness
  Temperate_Zone