diˈphosphate Chem. See di-2 2 and phosphate n. 1826Henry Elem.Chem. II. 121 There is also..a diphosphate, consisting of 1 atom of phosphoric acid and 2 atoms of the protoxide.c1865G. Gore in Circ.Sc. I. 220/2 Pyrophosphate of soda is easily formed by heating to redness the common diphosphate of soda.