noun Chemistry. 1.Also called monobasic sodium phosphate. a white, crystalline, slightly hygroscopic, water-soluble powder, NaH 2 PO 4 , used chiefly in dyeing and in electroplating.
2.Also called dibasic sodium phosphate, disodium phosphate. a water-soluble compound that in its anhydrous form, Na
2 HPO
4 , 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, Na
2 HPO
4 ⋅xH
2 O, 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, Na
3 PO
4 ⋅12H
2 O, occurring as crystals: used chiefly in the manufacture of water-softening agents, detergents, paper, and textiles.