'Hydration' definitions:

Definition of 'hydration'

(from WordNet)
noun
The process of combining with water; usually reversible

Definition of 'Hydration'

From: GCIDE
  • Hydration \Hy*dra"tion\, n. (Chem.) The act of becoming, or state of being, a hydrate. [1913 Webster]
  • Water of hydration (Chem.), water chemically combined with some substance to form a hydrate; -- distinguished from water of crystallization. [1913 Webster]