Source : Webster's Revised Unabridged Dictionary (1913)

Paroxysmal \Par`ox*ys"mal\, a.
   Of the nature of a paroxysm; characterized or accompanied by
   paroxysms; as, a paroxysmal pain; paroxysmal temper. --
   {Par`ox*ys"mal*ly}, adv.

Source : WordNet®

paroxysmal
     adj : accompanied by or of the nature of paroxysms