/ Dictionary / Index O orthophosphate: Meaning and Definition of Find definitions for: or•tho•phos•phate Pronunciation: (ôr"thu-fos'fāt), [key] — n. Chem. a salt or ester of orthophosphoric acid, or any compound containing the trivalent group −PO. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: orthophosphate (Thesaurus) orthopedics orthophosphoric acid Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language