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.
      [1913 Webster]

   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]

The Collaborative International Dictionary of English v.0.48:

Languishing \Lan"guish*ing\, a.
   1. Becoming languid and weak; pining; losing health and
      strength.
      [1913 Webster]

   2. Amorously pensive; indicating melancholy; as, languishing
      eyes, or look.
      [1913 Webster]

   3. Suffering neglect; neglected.
      [PJC]

   4. Continuing in a weak or deteriorating state; lingering.
      [PJC]

Moby Thesaurus II by Grady Ward, 1.0:

201 Moby Thesaurus words for "languishing":
   Heimweh, aching, adoring, affectionate, bowed-down, cachectic,
   cachexia, cachexy, cast down, chronic ill health, coming apart,
   conjugal, contractive, cracking, crumbling, dashed, debilitated,
   debilitation, debility, decadent, declining, decreasing,
   decrepitude, decrescendo, decrescent, degenerate, dejected,
   delicacy, delicate health, deliquescent, demonstrative, depressed,
   desiderium, despairing, despondent, desponding, deteriorating,
   devoted, diminishing, diminuendo, discouraged, disheartened,
   disintegrating, dispirited, down, downcast, downhearted, drained,
   draining, drawn-out, drooping, droopy, dwindling, ebbing, effete,
   enervated, enervation, enfeebled, exhausted, exhaustion, extended,
   fading, failing, faineant, faithful, falling, feeble, feebleness,
   feeling low, filial, flagging, fond, fragility, fragmenting, frail,
   frailty, going to pieces, hankering, healthless, healthlessness,
   heartless, homesick, homesickness, honing, husbandly, hypochondria,
   hypochondriac, hypochondriacal, hypochondriasis, ill health,
   in low spirits, in poor health, in the depths, in the doldrums,
   in the dumps, indolent, infirm, infirmity, interminable, invalid,
   invalidism, invalidity, lackadaisical, languishment, languorous,
   lasting, lengthened, lessening, limp, lingering, listless, long,
   long-continuing, long-drawn, long-drawn-out, long-pending,
   long-winded, longing, lovelorn, lovesick, lovesome, loving, low,
   low-spirited, mal du pays, maladie du pays, marathon, marcescent,
   maternal, melting, morbidity, morbidness, moribund, nostalgia,
   nostalgic, nostomania, on the wane, overlong, pale, parental,
   paternal, peaked, peakedness, peaky, pessimistic, pining,
   poor health, prolonged, protracted, reduced, reduced in health,
   reductive, regressive, retrograde, retrogressive, romantic,
   run-down, sentimental, shriveling, sickliness, sickly, sinking,
   sliding, slipping, slumping, soft, spiritless, spun-out,
   stretched-out, subdued, subsiding, suicidal, tabetic, tender,
   unhealthiness, unhealthy, unsound, unsoundness, unwholesomeness,
   uxorious, valetudinarian, valetudinarianism, valetudinary, waning,
   wasting, weakened, weakliness, weakly, weary of life, wifely,
   wilting, wishful, wistful, with low resistance, withering,
   woebegone, world-weary, worsening, yearnful, yearning, yen