- 1. Chemically, the addition of water; differentiated from hydrolysis, where the union with water is accompanied by a splitting of the original molecule and the water molecule. SEE ALSO: solvation. 2. Clinically, the taking in of water; used commonly in the sense of reduced h. or dehydration. 3. The formation of a shell of water molecules around a molecular entity.- absolute h. actual water excess as measured by a difference from the normal or from a given water content.
* * *hy·dra·tion hī-'drā-shən n1) the act or process of combining or treating with water: asa) the introduction of additional fluid into the body <\hydration sometimes helps to reduce the concentration of toxic substances in the tissues>b) a chemical reaction in which water takes part with the formation of only one product <\hydration of ethylene to ethyl alcohol> esp a reaction in which water takes part in the form of intact molecules2) the quality or state of being hydrated esp the condition of having adequate fluid in the body tissues
* * *hy·dra·tion (hi-draґshən) 1. the act of combining or causing to combine with water. 2. the condition of being combined with water.
Medical dictionary. 2011.