/ Dictionary / Index P phosphoric acid: Meaning and Definition of Find definitions for: phosphor'ic ac'id Pronunciation: [key] — Chem. Chem. any of three acids, orthophosphoric acid, HPO, metaphosphoric acid, HPO, or pyrophosphoric acid, HPO, derived from phosphorus pentoxide, PO, and various amounts of water. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. phosphoric phosphoric anhydride Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language