Hydroxyquinone often refers to a hydroxybenzoquinone, any organic compound with formula C6H4O3 which can be viewed as a derivative of a benzoquinone through replacement of one hydrogen atom (H) by a hydroxyl group (-OH).
That parent is sometimes simply called quinone, and this is the only hydroxy derivative of it.
More generally, the term may refer to any derivative of any quinone (such as 1,2-benzoquinone, 1,4-naphthoquinone or 9,10-anthraquinone), where any number n of hydrogens have been replaced by n hydroxyls.
In this case the number n is indicated by a multiplier prefix (mono-, di-, tri-, etc.
The hydroxyquinones (in the particular or the general sense) include many biologically and industrially important compounds, and are a building block of many medicinal drugs.