hypophosphateChem.|hɪpəʊ-, haɪpəʊˈfɒsfət| [f. hypo- 5 + phosphate n. So in F.] A salt of hypophosphoric acid. 1864in Webster.1894Roscoe & Schorlemmer Chem. I. 586 On neutralizing with caustic soda, a slightly soluble salt, sodium hypophosphate, H2Na2P2O6, separates out.