any member of either of two classes of compounds derived from nitric acid, HNO₃. The salts of nitric acid are ionic compounds containing the nitrate ion, NO^-₃, and a positive ion, such as NH₄⁺ in ammonium nitrate. Esters of nitric acid are covalent compounds having the structure R−O−NO₂, in which R represents an organic combining group, such as ethyl (C₂H₅) in ethyl nitrate. See also nitro compound.