/ Thesaurus / P Synonyms of pyrophosphoric acid Find synonyms for: Noun1. pyrophosphoric acid, polyphosphoric acidusage: a solid acid formed by reactions of orthophosphoric acidWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: diaphanous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language