(biology) the process of providing an adequate amount of water to body tissues
(construction) the chemical reaction by which a substance (such as cement) combines with water, giving off heat to form a crystalline structure in its setting and hardening.
“However, diffusive motion is present at all hydrations and temperatures studied, and the hydration-induced anharmonic motions are not required for activity.”
“In most cases, water adds in the direction that places the new hydroxyl group on the more highly substituted end of the double bond according to the Markovnikov rule, as in acid-catalyzed hydrations.”