The Collaborative International Dictionary of English v.0.48:

Restless \Rest"less\, a. [AS. restle['a]s.]
   1. Never resting; unquiet; uneasy; continually moving; as, a
      restless child. --Chaucer. "Restless revolution day by
      day." --Milton.
      [1913 Webster]

   2. Not satisfied to be at rest or in peace; averse to repose
      or quiet; eager for change; discontented; as, restless
      schemers; restless ambition; restless subjects. "Restless
      at home, and ever prone to range." --Dryden.
      [1913 Webster]

   3. Deprived of rest or sleep.
      [1913 Webster]

            Restless he passed the remnants of the night.
                                                  --Dryden.
      [1913 Webster]

   4. Passed in unquietness; as, the patient has had a restless
      night.
      [1913 Webster]

   5. Not affording rest; as, a restless chair. --Cowper.
      [1913 Webster]

   Restless thrush. (Zool.) See Grinder, 3.
      [1913 Webster]

   Syn: Unquiet; uneasy; disturbed; disquieted; sleepless;
        agitated; unsettled; roving; wandering.
        [1913 Webster] -- Rest"less*ly, adv.-
        Rest"less*ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

restless
    adj 1: worried and uneasy [syn: restless, ungratified,
           unsatisfied]
    2: ceaselessly in motion; "the restless sea"; "the restless
       wind"
    3: lacking or not affording physical or mental rest; "a restless
       night"; "she fell into an uneasy sleep" [syn: restless,
       uneasy] [ant: relaxing, reposeful, restful]

Moby Thesaurus II by Grady Ward, 1.0:

179 Moby Thesaurus words for "restless":
   adrift, afloat, agitated, alternating, amorphous, antsy,
   antsy-pantsy, anxious, apprehensive, beefing, bellyaching,
   bitching, breathless, bustling, capricious, chafing, changeable,
   changeful, complaining, complaintful, crabbing, crabby, cranky,
   croaking, desultory, deviable, disappointed, discomposed,
   discontented, disgruntled, displeased, disquieted, dissatisfied,
   disturbed, dizzy, eager, eccentric, edgy, envious, erratic,
   excitable, excited, fast and loose, faultfinding, feverish, fickle,
   fidgety, fitful, flickering, flighty, flitting, fluctuating,
   flurried, flustered, fluttering, fluttery, freakish, fretful,
   fretting, fussing, fussy, giddy, griping, grouchy, grousing,
   growling, grumbling, hasty, high-strung, hopped-up, hyper,
   impatient, impetuous, impulsive, in a lather, in a stew,
   in a sweat, inconsistent, inconstant, indecisive, infirm,
   insomniac, insomnious, intermittent, irregular, irresolute,
   irresponsible, itchy, jittery, jumpy, malcontent, malcontented,
   mazy, mercurial, moody, murmuring, muttering, nervous, nervy,
   on edge, on tenterhooks, out of humor, peevish, perturbed,
   petulant, querulant, querulous, rambling, rebellious, resentful,
   restive, roving, ruffled, scatterbrained, shaken, shaken up,
   shapeless, shifting, shifty, shuffling, skittish, sleepless,
   slumberless, spasmodic, spineless, squirming, squirmy, stirred up,
   sulky, tense, troubled, troublous, turbulent, unaccepting,
   unaccommodating, unaccountable, uncertain, uncontrolled,
   undependable, undisciplined, uneasy, unfixed, unfulfilled,
   ungratified, unhappy, unpatient, unpeaceful, unpredictable,
   unquiet, unreliable, unrestful, unrestrained, unsatisfied,
   unsettled, unsleeping, unstable, unstable as water, unstaid,
   unsteadfast, unsteady, upset, uptight, vacillating, vagrant,
   variable, vicissitudinary, vicissitudinous, volatile, wakeful,
   wandering, wanton, wavering, wavery, wavy, wayward, whimsical,
   whiny, wishy-washy, worked up