A compound formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts.
- A solid compound containing water molecules combined in a definite ratio as an integral part of the crystal.
- To rehydrate.
- To supply water to (a person, for example) in order to restore or maintain fluid balance: "Cold water is the fastest and safest way to hydrate an ordinary athlete” ( Jane E. Brody).
- To become a hydrate.