moody, temperamental - subject to sharply varying moods; "a temperamental opera singer" Antonym:unemotional (indirect, via emotional)
erratic, temperamental - likely to perform unpredictably; "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 Antonyms:reliable, dependable (indirect, via unreliable, undependable) Antonyms:reliable, dependable (indirect, via unreliable, undependable)