Answer: Called a Hydrate.
A hydrate is a compound that has a specific number of water molecules bound to its structure, forming a distinct crystalline structure. The water molecules in a hydrate are known as "water of hydration" and are chemically bound to the compound through hydrogen bonding. The number of water molecules in a hydrate is typically a whole number and is represented in the compound's formula with a dot followed by the number of water molecules, such as CuSO4·5H2O (copper(II) sulfate pentahydrate).
Hydrates can form when a compound with a high affinity for water is exposed to a moist environment or when a compound is dissolved in water. The water of hydration can be removed from a hydrate through heating, a process known as dehydration. Dehydration of a hydrate can result in a change in the compound's physical properties, such as color or crystal structure, and may also affect its chemical reactivity.