a colorless, crystalline powder, ZnSO·7HO, used as an emetic in medicine, as a mordant in dyeing, etc.
See zinc sulfate in American Heritage Dictionary 4
noun
A colorless crystalline compound, ZnSO4·7H2O, used medicinally as an emetic and astringent, as a fungicide, and in wood and skin preservatives. Also called white vitriol.