The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

   Tic douloureux. [F., fr. tic a knack, a twitching +
      douloureux painful.] (Med.) Neuralgia in the face; face
      ague. See under Face.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tic
    n 1: a local and habitual twitching especially in the face

Moby Thesaurus II by Grady Ward, 1.0:

100 Moby Thesaurus words for "tic":
   abstraction, abulia, agitation, alienation, anxiety,
   anxiety equivalent, anxiety state, apathy, apprehensiveness,
   attack of nerves, bob, bobble, bounce, buck fever, bump,
   case of nerves, catatonic stupor, complex, compulsion, dejection,
   depression, detachment, didder, dither, elation, emotionalism,
   euphoria, excessive irritability, falter, fascination, fear,
   fidgetiness, fidgets, fixation, fixed idea, folie du doute,
   grimace, hang-up, hypercathexis, hypochondria, hysteria, hysterics,
   idee fixe, indifference, insensibility, irresistible impulse, jar,
   jerk, jig, jigget, jiggle, jog, joggle, jolt, jostle, lethargy,
   mania, melancholia, mental distress, monomania, morbid drive,
   morbid excitability, nerves, nervosity, nervous stomach,
   nervousness, obsession, obsessive compulsion, panic, panickiness,
   pathological indecisiveness, possession, preoccupation,
   prepossession, psychalgia, psychomotor disturbance, quake, quaver,
   quiver, rictus, ruling passion, shake, shiver, shock, shudder,
   spell of nerves, stage fright, state of nerves, stupor, tremble,
   tremor, trepidation, twitch, twitching, twitter, uneasiness,
   unresponsiveness, vellication, withdrawal, wobble