The Collaborative International Dictionary of English v.0.48:

Numb \Numb\ (n[u^]m), a. [OE. nume, nome, prop., seized, taken,
   p. p. of nimen to take, AS. niman, p. p. numen. [root]7. See
   Nimble, Nomad, and cf. Benumb.]
   [1913 Webster]
   1. Enfeebled in, or destitute of, the power of sensation and
      motion; rendered torpid; benumbed; insensible; as, the
      fingers or limbs are numb with cold. "A stony image, cold
      and numb." --Shak.
      [1913 Webster]

   2. Producing numbness; benumbing; as, the numb, cold night.
      [Obs.] --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Numb \Numb\, v. t. [imp. & p. p. Numbed (n[u^]md); p. pr. &
   vb. n. Numbing (n[u^]m"[i^]ng).]
   To make numb; to deprive of the power of sensation or motion;
   to render senseless or inert; to deaden; to benumb; to
   stupefy.
   [1913 Webster]

         For lazy winter numbs the laboring hand. --Dryden.
   [1913 Webster]

         Like dull narcotics, numbing pain.       --Tennyson.
   [1913 Webster]

WordNet (r) 3.0 (2006):

numb
    adj 1: lacking sensation; "my foot is asleep"; "numb with cold"
           [syn: asleep(p), benumbed, numb]
    2: (followed by `to') not showing human feeling or sensitivity;
       unresponsive; "passersby were dead to our plea for help";
       "numb to the cries for mercy" [syn: dead(p), numb(p)]
    3: so frightened as to be unable to move; stunned or paralyzed
       with terror; petrified; "too numb with fear to move"
    v 1: make numb or insensitive; "The shock numbed her senses"
         [syn: numb, benumb, blunt, dull]

Moby Thesaurus II by Grady Ward, 1.0:

165 Moby Thesaurus words for "numb":
   KO, Laodicean, Olympian, abate, allay, alleviate, aloof,
   anesthetize, anesthetized, apathetic, appease, asleep, assuage,
   bedaze, benumb, benumbed, besot, bite, blah, blase, blunt, bored,
   callous, casual, chill, chloroform, coldcock, comatose, cushion,
   cut, dead, deaden, deaden the pain, deadened, debilitated,
   desensitize, desensitized, detached, diminish, disinterested, dope,
   dopey, dormant, droopy, drug, drugged, dull, ease, ease matters,
   enervated, etherize, exanimate, foment, freeze, frost, frostbite,
   give relief, go through, heartless, heavy, hebetudinous, hopeless,
   immobilize, impassible, imperceptive, impercipient, in a stupor,
   inanimate, incurious, indifferent, inert, insensate, insensible,
   insensitive, insentient, insouciant, jaded, kayo, knock out,
   knock senseless, knock stiff, knock unconscious, lackadaisical,
   languid, languorous, lay, lay out, leaden, lessen, lethargic,
   lifeless, listless, lull, lumpish, mitigate, mollify, moribund,
   mull, narcotize, nip, nonchalant, numbed, obdurate, obtund, obtuse,
   pad, palliate, palsy, paralyze, passive, penetrate, phlegmatic,
   pierce, pluckless, pooped, poultice, pour balm into, pour oil on,
   put to sleep, reduce, refrigerate, relieve, remote, resigned,
   salve, sated, senseless, slack, slacken, slake, sleepy, slow,
   sluggish, soften, somnolent, soothe, soporific, spiritless,
   spunkless, stagnant, stagnating, stoic, stultified, stun, stupe,
   stupefied, stupefy, subdue, supine, thick-skinned, thick-witted,
   torpid, uncaring, unconcerned, unconscious, unfeeling, unfelt,
   uninterested, unperceptive, vegetable, vegetative, wan, weary,
   withdrawn, world-weary