Source : Webster's Revised Unabridged Dictionary (1913)

Tic \Tic\, n. [F.] (Med.)
   A local and habitual convulsive motion of certain muscles;
   especially, such a motion of some of the muscles of the face;
   twitching; velication; -- called also {spasmodic tic}.
   --Dunglison.

   {Tic douloureux}. [F., fr. tic a knack, a twitching +
      douloureux painful.] (Med.) Neuralgia in the face; face
      ague. See under {Face}.

Source : WordNet®

tic
     n : a local and habitual twitching especially in the face