The Collaborative International Dictionary of English v.0.48:

Torpor \Tor"por\, n. [L., from torpere, to be torpid.]
   [1913 Webster]
   1. Loss of motion, or of the motion; a state of inactivity
      with partial or total insensibility; numbness.
      [1913 Webster]

   2. Dullness; sluggishness; inactivity; as, a torpor of the
      mental faculties.
      [1913 Webster]

WordNet (r) 3.0 (2006):

torpor
    n 1: a state of motor and mental inactivity with a partial
         suspension of sensibility; "he fell into a deep torpor"
         [syn: torpor, torpidity]
    2: inactivity resulting from lethargy and lack of vigor or
       energy [syn: listlessness, torpidity, torpidness,
       torpor]

Moby Thesaurus II by Grady Ward, 1.0:

133 Moby Thesaurus words for "torpor":
   abeyance, abidingness, acedia, aloofness, apathy, ataraxia,
   ataraxy, benumbedness, blah, blahs, boredom, catalepsy, catatonia,
   changelessness, coma, comatoseness, constancy, deadliness,
   deathliness, detachment, disinterest, dispassion, dormancy,
   drowsiness, dullness, durability, durableness, duration, endurance,
   enervation, ennui, entropy, fatigue, firmness, fixedness,
   frozenness, hardening, heartlessness, heaviness, hebetude,
   hopelessness, idleness, immobility, immovability, immovableness,
   immutability, inactivity, inanimation, inappetence, indifference,
   indolence, inertia, inertness, insouciance, invariability,
   invariableness, inveteracy, jadedness, just being,
   lack of appetite, lackadaisicalness, languidness, languishment,
   languor, languorousness, lassitude, lastingness, latency, laziness,
   lenitude, lentor, lethargicalness, lethargy, lifelessness,
   listlessness, long standing, lotus-eating, mere existence,
   mere tropism, nonchalance, numbness, oscitancy, passiveness,
   passivity, permanence, permanency, perpetualness, persistence,
   persistency, phlegm, phlegmaticalness, phlegmaticness,
   plucklessness, pococurantism, quiescence, resignation,
   resignedness, rigidity, satedness, sleep, sleepiness, sloth,
   slothfulness, slowness, sluggishness, solidity, somnolence, sopor,
   soporifousness, spiritlessness, spunklessness, stability,
   stagnancy, stagnation, standing, stasis, steadfastness, stolidity,
   stupefaction, stupor, supineness, suspense, torpidity, torpidness,
   torpitude, unchangeability, unchangingness, unconcern, vegetation,
   vis inertiae, weariness, withdrawnness, world-weariness