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):

restlessness
    n 1: the quality of being ceaselessly moving or active; "the
         restlessness of the wind"
    2: a lack of patience; irritation with anything that causes
       delay [syn: restlessness, impatience]
    3: a feeling of agitation expressed in continual motion; "he's
       got the fidgets"; "waiting gave him a feeling of
       restlessness" [syn: fidget, fidgetiness, restlessness]
    4: inability to rest or relax or be still [syn: restlessness,
       uneasiness, queasiness]

Moby Thesaurus II by Grady Ward, 1.0:

207 Moby Thesaurus words for "restlessness":
   Faustianism, activity, actuation, ado, agitation, ailment,
   alertness, all-night vigil, anxiety, bluster, bobbery, boil,
   boiling, bother, botheration, breathless impatience, brouhaha,
   burst, bustle, capriciousness, chafing, churn, cold comfort,
   commotion, consciousness, conturbation, desultoriness, deviability,
   didder, disappointment, discomposure, discontent, discontentedness,
   discontentment, disgruntlement, disorder, disquiet, disquietude,
   dissatisfaction, dissatisfiedness, disturbance, dithers,
   divine discontent, dynamics, eagerness, ebullition, eccentricity,
   embroilment, envy, erraticism, excitement, feery-fary, ferment,
   fermentation, fever, feverishness, fickleness, fidgetiness,
   fidgets, fit, flap, flightiness, flurry, fluster, flutter,
   flutteration, flutteriness, foment, freakishness, fretfulness,
   fretting, fume, fuss, fussiness, going, haste, heaving, hubbub,
   hullabaloo, hurly-burly, ill humor, impatience, impatientness,
   impetuousness, impulsiveness, inconsistency, inconstancy,
   inquietude, insomnia, insomniac, insomnolence, insomnolency,
   instability, irregularity, jitters, jumpiness, kinematics,
   kinesipathy, kinesis, kinesitherapy, kinetics, lather,
   lidless vigil, maelstrom, malaise, mercuriality, mobilization,
   moil, moodiness, motion, motivation, move, movement, moving,
   nerviness, nervosity, nervousness, palpitation, panting,
   peevishness, perturbation, petulance, pitapat, pitter-patter,
   pother, quaking, quaver, quavering, querulousness, quiver,
   quivering, rebelliousness, resentment, restiveness, roil, rout,
   row, running, scramble, seethe, seething, sentience, shakes,
   shaking, shiftiness, shiver, shivers, shudder, sleeplessness,
   sourness, spasm, spurt, stew, stir, stirring, sulkiness, sweat,
   swirl, tense readiness, throb, throbbing, to-do,
   tossing and turning, tremble, trembling, tremor, trepidation,
   trepidity, tumult, tumultuation, turbidity, turbulence, turmoil,
   twitter, uncertainty, undependability, unease, uneasiness,
   unfixedness, unfulfillment, unhappiness, unpatientness, unpleasure,
   unpredictability, unquiet, unquietness, unreliability, unrest,
   unsatisfaction, unsettledness, unstableness, unsteadfastness,
   unsteadiness, upset, variability, variation, variety, velocity,
   vexation of spirit, vigil, vortex, wake, wakefulness, wantonness,
   waywardness, whimsicality, whirl