The Collaborative International Dictionary of English v.0.48:

Wither \With"er\, v. i. [imp. & p. p. Withered; p. pr. & vb.
   n. Withering.] [OE. wideren; probably the same word as
   wederen to weather (see Weather, v. & n.); or cf. G.
   verwittern to decay, to be weather-beaten, Lith. vysti to
   wither.]
   [1913 Webster]
   1. To fade; to lose freshness; to become sapless; to become
      sapless; to dry or shrivel up.
      [1913 Webster]

            Shall he hot pull up the roots thereof, and cut off
            the fruit thereof, that it wither?    --Ezek. xvii.
                                                  9.
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   2. To lose or want animal moisture; to waste; to pin? away,
      as animal bodies.
      [1913 Webster]

            This is man, old, wrinkled, faded, withered. --Shak.
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            There was a man which had his hand withered. --Matt.
                                                  xii. 10.
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            Now warm in love, now with'ring in the grave.
                                                  --Dryden.
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   3. To lose vigor or power; to languish; to pass away. "Names
      that must not wither." --Byron.
      [1913 Webster]

            States thrive or wither as moons wax and wane.
                                                  --Cowper.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Wither \With"er\, v. t.
   1. To cause to fade, and become dry.
      [1913 Webster]

            The sun is no sooner risen with a burning heat, but
            it withereth the grass, and the flower thereof
            falleth.                              --James i. 11.
      [1913 Webster]

   2. To cause to shrink, wrinkle, or decay, for want of animal
      moisture. "Age can not wither her." --Shak.
      [1913 Webster]

            Shot forth pernicious fire
            Among the accursed, that withered all their
            strength.                             --Milton.
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   3. To cause to languish, perish, or pass away; to blight; as,
      a reputation withered by calumny.
      [1913 Webster]

            The passions and the cares that wither life.
                                                  --Bryant.
      [1913 Webster]

WordNet (r) 3.0 (2006):

wither
    v 1: wither, as with a loss of moisture; "The fruit dried and
         shriveled" [syn: shrivel, shrivel up, shrink,
         wither]
    2: lose freshness, vigor, or vitality; "Her bloom was fading"
       [syn: fade, wither]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "wither":
   Sanforize, age, air-dry, anhydrate, attenuate, bake, blot, brush,
   burn, cave in, cheat the undertaker, collapse, constrict, consume,
   contract, cure, decline, deflate, dehumidify, dehydrate, desiccate,
   diminish, dodder, drain, droop, dry, dry up, dwindle, emacerate,
   emaciate, evaporate, exsiccate, fade, fade away, fail, fire, flag,
   fold, get along, get on, grow old, insolate, kiln, languish,
   lose strength, macerate, mummify, mummy, parch, peak, pine,
   preshrink, rub, run down, scorch, sear, shake, shrink, shrivel,
   sink, smoke, soak up, sponge, sun, sun-dry, swab, thin, torrefy,
   totter, towel, turn gray, turn white, wane, waste, waste away,
   weaken, weazen, welter, wilt, wipe, wither away, wizen, wrinkle