1. (loosely) a salt or ester of phosphoric acid.
  2. a tertiary salt of orthophosphoric acid, as sodium phosphate.
Agriculture. a fertilizing material containing compounds of phosphorus.
a carbonated drink of water and fruit syrup containing a little phosphoric acid.

Origin of phosphate

First recorded in 1785–95; phosph- + -ate2
Related formssub·phos·phate, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for phosphate



any salt or ester of any phosphoric acid, esp a salt of orthophosphoric acid
(often plural) any of several chemical fertilizers containing phosphorous compounds
Derived Formsphosphatic (fɒsˈfætɪk), adjective

Word Origin for phosphate

C18: from French phosphat; see phosphorus, -ate 1
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

Word Origin and History for phosphate

a salt of phosphoric acid, 1795, from French phosphate (1787), from phosphore (see phosphorus) + -ate (3).

Online Etymology Dictionary, © 2010 Douglas Harper

phosphate in Medicine




A salt or ester of phosphoric acid.


Containing the trivalent radical PO4.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

phosphate in Science



A salt or ester of phosphoric acid, containing the group PO4. Phosphates are important in metabolism and are frequently used in fertilizers.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.