Chem. 1. Also called monobasic sodium phosphate. a white, crystalline, slightly hygroscopic, water-soluble powder, NaH2PO4, used chiefly in dyeing and in electroplating.
2. Also called dibasic sodium phosphate, disodium phosphate. a water-soluble compound that in its anhydrous form, Na2HPO4, occurring as a white, crystalline, hygroscopic powder, is used chiefly in the manufacture of ceramic glazes, enamels, baking powder, and cheeses, and that in its hydrated form, Na2HPO4·xH2O, occurring as clear colorless crystals, is used chiefly in the manufacture of dyes, fertilizers, detergents, and pharmaceuticals.
3. Also called tribasic sodium phosphate, trisodium phosphate, TSP. a colorless water-soluble compound, Na3PO4·12H2O, occurring as crystals: used chiefly in the manufacture of water-softening agents, detergents, paper, and textiles.