The Collaborative International Dictionary of English v.0.48:

Languish \Lan"guish\, v. i.
   To cause to droop or pine. [Obs.] --Shak. --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Languish \Lan"guish\, n.
   See Languishment. [Obs. or Poetic]
   [1913 Webster]

         What, of death, too,
         That rids our dogs of languish?          --Shak.
   [1913 Webster]

         And the blue languish of soft Allia's eye. --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Languish \Lan"guish\, v. i. [imp. & p. p. Languished; p. pr. &
   vb. n. Languishing.] [OE. languishen, languissen, F.
   languir, L. languere; cf. Gr. ? to slacken, ? slack, Icel.
   lakra to lag behind; prob. akin to E. lag, lax, and perh. to
   E. slack. See -ish.]
   1. To become languid or weak; to lose strength or animation;
      to be or become dull, feeble or spiritless; to pine away;
      to linger in a weak or deteriorating condition; to wither
      or fade.
      [1913 Webster]

            We . . . do languish of such diseases. --2 Esdras
                                                  viii. 31.
      [1913 Webster]

            Cease, fond nature, cease thy strife,
            And let me languish into life.        --Pope.
      [1913 Webster]

            For the fields of Heshbon languish.   --Is. xvi. 8.
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   2. To assume an expression of weariness or tender grief,
      appealing for sympathy. --Tennyson.

   3. To be neglected and unattended to; as, the proposal
      languished on the director's desk for months.
      [PJC]

   Syn: To pine; wither; fade; droop; faint.
        [1913 Webster]

WordNet (r) 3.0 (2006):

languish
    v 1: lose vigor, health, or flesh, as through grief; "After her
         husband died, she just pined away" [syn: pine away,
         waste, languish]
    2: have a desire for something or someone who is not present;
       "She ached for a cigarette"; "I am pining for my lover" [syn:
       ache, yearn, yen, pine, languish]
    3: become feeble; "The prisoner has be languishing for years in
       the dungeon" [syn: languish, fade]

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "languish":
   abate, ablate, bate, be eaten away, become suicidal, break,
   cave in, collapse, come apart, come unstuck, conk out, consume,
   consume away, corrode, crumble, decline, decrease, deliquesce,
   desiccate, despair, despond, deteriorate, die away, diminish,
   disintegrate, dive, droop, drop, drop off, dry up, dwindle, ebb,
   erode, fade, fade away, fail, faint, fall, fall away, fall off,
   fizzle out, flag, give out, give way, go downhill, go soft,
   go to pieces, hit rock bottom, hit the skids, lessen, let up,
   lose heart, lose strength, melt away, peak, peg out, peter out,
   pine, plumb the depths, plummet, plunge, poop out,
   reach the depths, run down, run low, sag, sear, shrink, shrivel,
   sink, subside, tail off, touch bottom, wane, waste, waste away,
   weaken, wear, wear away, wear thin, wilt, wither, wither away,
   wizen, yield