Adjective

• S: (adj) erratic, fickle, mercurial, quicksilver (liable to sudden unpredictable change) "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next"
• S: (adj) erratic, planetary, wandering (having no fixed course) "an erratic comet"; "his life followed a wandering course"; "a planetary vagabond"
• S: (adj) 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