/ Thesaurus / O Synonyms of orthophosphoric acid Find synonyms for: Noun1. phosphoric acid, orthophosphoric acid, oxyacid, oxygen acidusage: an acid used in fertilizers and soaps: H3PO4WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language