Dehydration

n. drying up; loss of water; abnormal lack of water in the body due to insufficient intake of liquids or extreme loss of fluids by sweating or vomiting or due to diarrhea (Medicine); lack of water; removal of water, removal of moisture

Dehydration (hypohydration) is the removal of water (hydro in ancient Greek) from an object. Medically, it is a condition in which the body contains an insufficient volume of water for normal functioning.
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Dehydration is the loss of water and salts essential for normal body function. [more]Dehydration - Community and Resources

Noun
1. dryness resulting from the removal of water
(synonym) desiccation
(hypernym) dryness, waterlessness, xerotes
(derivation) dehydrate, desiccate
2. depletion of bodily fluids
(hypernym) thirst
(derivation) dehydrate, desiccate
3. the process of extracting moisture
(synonym) desiccation, drying up, evaporation
(hypernym) extraction
(hyponym) freeze-drying, lyophilization, lyophilisation
(part-holonym) plastination
(derivation) dehydrate, desiccate

(n.)
The act or process of freeing from water; also, the condition of a body from which the water has been removed.