Source : Webster's Revised Unabridged Dictionary (1913)

Antispasmodic \An`ti*spas*mod"ic\, a. (Med.)
   Good against spasms. -- n. A medicine which prevents or
   allays spasms or convulsions.

Source : WordNet®

antispasmodic
     n : a drug used to relieve or prevent spasms (especially of the
         smooth muscles) [syn: {spasmolytic}, {antispasmodic agent}]