Source : Webster's Revised Unabridged Dictionary (1913)

Temperamental \Tem`per*a*men"tal\, a.
   Of or pertaining to temperament; constitutional. [R.] --Sir
   T. Browne.

Source : WordNet®

temperamental
     adj 1: relating to or caused by temperament; "temperamental
            indifference to neatness"; "temperamental
            peculiarities"
     2: subject to sharply varying moods; "a temperamental opera
        singer" [syn: {moody}]
     3: 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
        [syn: {erratic}]