Compounds in which one or more of the OH groups of phosphoric acid have been replaced with an amino or substituted amino group; commonly confined to the phosphoric triamides, $\ce{P(=O)(NR2)3, since replacement of one or two $\ce{OH}$ groups produces phosphoramidic acids $\ce{P(=O)(OH)(NR2)2}$, $\ce{P(=O)(OH)2(NR2)}$.