The Collaborative International Dictionary of English v.0.48:

dehydrate \de*hy"drate\, v. t.
   To deprive of water; to render free from water; as, to
   dehydrate alcohol; to dehydrate food for preservation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

dehydrate \de*hy"drate\, v. i.
   1. to lose water or moisture.
      [PJC]

   2. to lose sufficent water to cause physiological distress;
      -- of living organisms; as, victims trapped in the
      earthquake rubble may dehydrate if not found quickly.
      [PJC]

WordNet (r) 3.0 (2006):

dehydrate
    v 1: preserve by removing all water and liquids from; "carry
         dehydrated food on your camping trip" [syn: dehydrate,
         desiccate]
    2: remove water from; "All this exercise and sweating has
       dehydrated me" [syn: dehydrate, desiccate]
    3: lose water or moisture; "In the desert, you get dehydrated
       very quickly" [syn: exsiccate, dehydrate, dry up,
       desiccate] [ant: hydrate]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "dehydrate":
   air-dry, anhydrate, bake, blast-freeze, blot, brine, brush, burn,
   corn, cure, dehumidify, desiccate, drain, dry, dry-cure, dry-salt,
   embalm, evaporate, exsiccate, fire, freeze, freeze-dry, fume,
   insolate, irradiate, jerk, kiln, kipper, marinade, marinate,
   mummify, parch, pickle, preservatize, quick-freeze, refrigerate,
   rub, salt, scorch, sear, season, shrivel, smoke, smoke-cure,
   soak up, sponge, stuff, sun, sun-dry, swab, torrefy, towel, weazen,
   wipe, wither, wizen