Hydrate
Hydrates are compounds formed by the union of water and another substance, a union generally resulting in a neutral body, like certain crystallized salts. If water is heavy water, where hydrogen is actually deuterium, the term deuterate is used instead of hydrous. These so-called hydrated substances do not contain water as such, but their elements or their combination: hydrogen, oxygen or hydroxyl. However, and by abuse, it is often said that the hydrated compounds contain water, as opposed to anhydrous. In some cases, water can form clathrates which are also called hydrates, for example, methane hydrate.