The Collaborative International Dictionary of English v.0.48:

Twitch \Twitch\, v. t. [imp. & p. p. Twitched; p. pr. & vb. n.
   Twitching.] [OE. twicchen, fr. (doubtful) AS. twiccian;
   akin to AS. angeltwicca a worm used for bait, literally, a
   hook twitcher, LG. twikken to tweak, G. zwicken. Cf.
   Tweak.]
   To pull with a sudden jerk; to pluck with a short, quick
   motion; to snatch; as, to twitch one by the sleeve; to twitch
   a thing out of another's hand; to twitch off clusters of
   grapes.
   [1913 Webster]

         Thrice they twitched the diamond in her ear. --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Twitch \Twitch\, n.
   1. The act of twitching; a pull with a jerk; a short, sudden,
      quick pull; as, a twitch by the sleeve.
      [1913 Webster]

   2. A short, spastic contraction of the fibers or muscles; a
      simple muscular contraction; as, convulsive twitches; a
      twitch in the side.
      [1913 Webster]

   3. (Far.) A stick with a hole in one end through which passes
      a loop, which can be drawn tightly over the upper lip or
      an ear of a horse. By twisting the stick the compression
      is made sufficiently painful to keep the animal quiet
      during a slight surgical operation. --J. H. Walsh.
      [1913 Webster]

WordNet (r) 3.0 (2006):

twitch
    n 1: a sudden muscle spasm; especially one caused by a nervous
         condition [syn: twitch, twitching, vellication]
    v 1: make an uncontrolled, short, jerky motion; "his face is
         twitching" [syn: twitch, jerk]
    2: move with abrupt, seemingly uncontrolled motions; "The
       patient's legs were jerkings" [syn: jerk, twitch]
    3: toss with a sharp movement so as to cause to turn over in the
       air [syn: flip, twitch]
    4: squeeze tightly between the fingers; "He pinched her behind";
       "She squeezed the bottle" [syn: pinch, squeeze, twinge,
       tweet, nip, twitch]
    5: move or pull with a sudden motion

Moby Thesaurus II by Grady Ward, 1.0:

153 Moby Thesaurus words for "twitch":
   ache, acute pain, agonize, ail, anguish, bite, blanch, blench, bob,
   bobble, boring pain, bounce, breath, bump, charley horse, clutch,
   coup, crack, cramp, cramps, crick, darting pain, didder, dither,
   falter, feel pain, feel the pangs, fidget, flash, flick, flip,
   flip out, flirt, flounce, flutter, freak out on, fulgurant pain,
   get high on, girdle pain, glow, gnawing, go pitapat, grasp,
   grimace, griping, half a jiffy, half a mo, half a second,
   half a shake, have a misery, have the fidgets, have the shakes,
   heave, hitch, hurt, instant, itch, jar, jerk, jiff, jiffy, jig,
   jigger, jigget, jiggle, jog, joggle, jolt, jostle, jumping pain,
   kink, lancinating pain, lug, lurch, microsecond, millisecond,
   minute, moment, nip, palpitate, pang, pant, paroxysm, pinch, pluck,
   pound, prick, quake, quaver, quiver, rictus, sec, second, seizure,
   shake, sharp pain, shiver, shock, shoot, shooting, shooting pain,
   shrink, shudder, smart, snake, snap, snatch, spasm, split second,
   squirm, stab, stabbing pain, start, stitch, stroke, sudden pull,
   suffer, swell, swell with emotion, thrill, thrill to, throb,
   throes, tic, tick, tingle, tingle with excitement, tormen, toss,
   toss and turn, tremble, tremor, trice, tumble, turn on to, tweak,
   twinge, twink, twinkle, twinkling, twist and turn, twitter,
   two shakes, vellicate, wiggle, wince, wink, wobble, wrench,
   wriggle, writhe, yank, yerk