Hydrate

In chemistry, a hydrate is a compound that has discrete water molecules combined with it. The water is known as water of crystallization and the number of water molecules associated with one molecule of the compound is denoted in both its name and chemical formula.

Example:

copper(II) sulphate pentahydrate (CuSO₄·5H₂O)

See also: Anhydrous, Water of Crystallization.