acid - any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt

hypophosphoric acid - a crystalline tetrabasic acid (H4P2O6)

hypophosphorous acid, orthophosphorous acid, phosphorous acid - a clear or yellow-colored monobasic acid (H3PO2)

polyphosphoric acid - a series of oxyacids of phosphorus

periodic acid - any oxygen-containing acid of iodine

orthophosphoric acid, phosphoric acid - an acid used in fertilizers and soaps: H3PO4

tungstic acid - an oxyacid of tungsten (often polymeric in nature) formed by neutralizing alkaline tungstate solutions

vanadic acid, vanadium pentoxide - any of various oxyacids of vanadium; known mostly in the form of its salts