The Collaborative International Dictionary of English v.0.48:

Spasmodic \Spas*mod"ic\, n. (Med.)
   A medicine for spasm.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spasmodic \Spas"mod"ic\, a. [Gr. ?; ? a convulsion + ? likeness:
   cf. F. spasmotique.]
   1. (Med.) Of or pertaining to spasm; consisting in spasm;
      occuring in, or characterized by, spasms; as, a spasmodic
      asthma.
      [1913 Webster]

   2. Soon relaxed or exhausted; convulsive; intermittent; as,
      spasmodic zeal or industry.
      [1913 Webster]

   Spasmodic croup (Med.), an affection of childhood
      characterized by a stoppage of brathing developed suddenly
      and without fever, and produced by spasmodic contraction
      of the vocal cords. It is sometimes fatal. Called also
      laryngismus stridulus, and childcrowing.

   Spasmodic stricture, a stricture caused by muscular spasm
      without structural change. See Organic stricture, under
      Organic.
      [1913 Webster]

WordNet (r) 3.0 (2006):

spasmodic
    adj 1: affected by involuntary jerky muscular contractions;
           resembling a spasm; "convulsive motions"; "his body made
           a spasmodic jerk"; "spastic movements" [syn:
           convulsive, spasmodic, spastic]
    2: occurring in spells and often abruptly; "fitful bursts of
       energy"; "spasmodic rifle fire" [syn: fitful, spasmodic]