Dictionary.com
definitions

orthophosphoric acid

[awr-thoh-fos-fawr-ik, -for-, awr-]
noun Chemistry.
  1. a colorless, crystalline solid, H3PO4, the tribasic acid of pentavalent phosphorus: used chiefly in fertilizers, as a source of phosphorus salts, and in soft drinks as an acidulant and flavoring agent.

Origin of orthophosphoric acid

First recorded in 1870–75; ortho- + phosphoric acid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for ortho-phosphoric acid

orthophosphoric acid

noun
  1. a colourless soluble solid tribasic acid used in the manufacture of fertilizers and soaps. Formula: H 3 PO 4Also called: phosphoric acid
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
ortho-phosphoric acid in Medicine

orthophosphoric acid

[ôr′thō-fŏs-fôr′ĭk]
n.
  1. phosphoric acid
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.