The Collaborative International Dictionary of English v.0.48:

Dehydration \De`hy*dra"tion\, n. (Chem.)
   The act or process of freeing from water; also, the condition
   of a body from which the water has been removed.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dehydration
    n 1: dryness resulting from the removal of water [syn:
         dehydration, desiccation]
    2: depletion of bodily fluids
    3: the process of extracting moisture [syn: dehydration,
       desiccation, drying up, evaporation]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "dehydration":
   air-drying, anhydration, blast-freezing, bottling, brining,
   canning, corning, curing, dehumidification, desiccation, drainage,
   dry-curing, drying, drying up, embalming, evaporation,
   freeze-drying, freezing, fuming, insolation, irradiation, jerking,
   marination, mummification, pickling, potting, quick-freezing,
   refrigeration, salting, seasoning, smoking, stuffing, taxidermy,
   tinning, withering