- A chemical compound, especially an ionic compound, containing a hydroxyl group.
- A hydrate; a substance containing hydrogen and oxygen, made by combining water with an oxide, and yielding water by elimination. The hydroxides are regarded as compounds of hydroxyl, united usually with basic element or radical.
- An <xref>univalent</xref> <xref>anion</xref> (OH-1) based on the <xref>hydroxyl</xref> <xref>functional group</xref>.
- Any <xref>substance</xref> containing such an anion.
- a compound of an oxide with water
- a chemical compound containing the hydroxyl group