Source : Webster's Revised Unabridged Dictionary (1913)

Petit mal \Pe*tit" mal"\ [F., lit., little sickness.] (Med.)
   The mildest form of epilepsy, with momentary faintness or
   unconsciousness, but without convulsions; -- opposed to
   {grand mal}.

Source : WordNet®

petit mal
     n : a seizure (or a type of epilepsy characterized by such
         seizures) of short duration characterized by momentary
         unconsciousness and local muscle spasms or twitching
         [syn: {epilepsia minor}]