The Collaborative International Dictionary of English v.0.48:

Fidget \Fidg"et\, v. i. [imp. & p. p. Fidgeted; p. pr. & vb.
   n. Fodgeting.] [From Fidge; cf. OE. fiken to fidget, to
   flatter, Icel. fika to hasten, Sw. fika to hunt after, AS.
   befician to deceive. Cf. Fickle.]
   To move uneasily one way and the other; to move irregularly,
   or by fits and starts. --Moore.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fidget \Fidg"et\, n.
   1. Uneasiness; restlessness. --Cowper.
      [1913 Webster]

   2. pl. A general nervous restlessness, manifested by
      incessant changes of position; dysphoria. --Dunglison.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fidget
    n 1: a feeling of agitation expressed in continual motion; "he's
         got the fidgets"; "waiting gave him a feeling of
         restlessness" [syn: fidget, fidgetiness,
         restlessness]
    v 1: move restlessly; "The child is always fidgeting in his
         seat"

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "fidget":
   chafe, coquet, dabble, dally, dither, fiddle, fiddle with,
   fiddle-faddle, fidget with, fidgetiness, finger with, flip out,
   flirt, flutter, fool, fool around, fool with, freak out on, fret,
   fribble, frivol, fuss, fuss-budget, fusspot, get high on, glow,
   go pitapat, have the fidgets, have the jitters, have the shakes,
   heave, heebie-jeebies, horse around, idle, itch, itchiness, jerk,
   jerk off, jig, jigger, jigget, jiggle, jitter, kid around, loiter,
   mess around, monkey, monkey around, nervousness, palpitate, pant,
   piddle, play, play around, play with, potter, putter, quake,
   quaver, quiver, restlessness, shake, shiver, shuffle, smatter,
   squirm, swell, swell with emotion, thrill, thrill to, throb,
   tingle, tingle with excitement, tinker, toss, toss and turn, toy,
   toy with, tremble, trifle, tumble, turn on to, twiddle,
   twist and turn, twitch, twitter, uneasiness, vellicate, wiggle,
   wriggle, writhe