The Collaborative International Dictionary of English v.0.48:

Enervate \E*ner"vate\, v. t. [imp. & p. p. Enervated; p. pr. &
   vb. n. Enervating.] [L. enervatus, p. p. of enervare, fr.
   enervis nerveless, weak; e out + nervus nerve. See Nerve.]
   To deprive of nerve, force, strength, or courage; to render
   feeble or impotent; to make effeminate; to impair the moral
   powers of.
   [1913 Webster]

         A man . . . enervated by licentiousness. --Macaulay.
   [1913 Webster]

         And rhyme began t' enervate poetry.      --Dryden.

   Syn: To weaken; enfeeble; unnerve; debilitate.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

enervated \enervated\ adj.
   lacking strength or vigor.

   Syn: adynamic, asthenic, debilitated.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

enervated
    adj 1: lacking strength or vigor [syn: adynamic, asthenic,
           debilitated, enervated]

Moby Thesaurus II by Grady Ward, 1.0:

143 Moby Thesaurus words for "enervated":
   apathetic, ausgespielt, benumbed, blase, bored, burned-out,
   cachectic, castrated, dead, debilitated, decadent, degenerate,
   demasculinized, deteriorated, devil, devitalized, disabled, dopey,
   dormant, drained, drooping, droopy, drugged, dull, effeminized,
   effete, emasculate, emasculated, enfant terrible, enfeebled,
   eunuchized, eviscerated, exanimate, exhausted, fagged, failing,
   faint, fainting, fatigued, feeble, feeling faint, flagging,
   footsore, frail, frazzled, gelded, good and tired, healthless,
   heavy, hebetudinous, in poor health, inanimate, incapacitated,
   inert, infirm, invalid, jaded, lackadaisical, languid, languishing,
   languorous, leaden, lethargic, lifeless, limb, limp, listless,
   lumpish, lustless, marrowless, mischief, moribund, nerveless, numb,
   pale, peaked, peaky, phlegmatic, pithless, played out, pooped,
   rapscallion, rascal, ready to drop, reduced, reduced in health,
   rogue, run ragged, run-down, sagging, sapped, sated, scalawag,
   seedy, sickly, sinewless, sleepy, slow, sluggish, somnolent, spent,
   spiritless, stagnant, stagnating, stultified, supine, tired,
   tired-winged, toilworn, torpid, unhealthy, unmanned, unnerved,
   unrefreshed, unrestored, unsexed, unsound, used up, valetudinarian,
   valetudinary, vegetable, vegetative, villain, wan, wasted,
   way-weary, wayworn, weak, weakened, weakly, wearied, weariful,
   weary, weary-footed, weary-laden, weary-winged, weary-worn,
   wilting, with low resistance, world-weary, worn, worn-down,
   worn-out