Webster's Revised Unabridged Dictionary · 1913

Hydrate

Hydrate , noun

[Greek "y`dwr water: compare French hydrate.]

(a)
(Chemistry) A compound formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts.
(b)
(Chemistry) A substance which does not contain water as such, but has its constituents (hydrogen, oxygen, hydroxyl) so arranged that water may be eliminated; hence, a derivative of, or compound with, hydroxyl; hydroxide; as, ethyl hydrate, or common alcohol; calcium hydrate, or slaked lime.

Hydrate , transitive verb

To form into a hydrate; to combine with water.