Source : Webster's Revised Unabridged Dictionary (1913)

Tantrum \Tan"trum\, n.
   A whim, or burst of ill-humor; an affected air. [Colloq.]
   --Thackeray.

Source : WordNet®

tantrum
     n : a display of bad temper; "he had a fit"; "she threw a
         tantrum"; "he made a scene" [syn: {fit}, {scene}, {conniption}]