phosphate

noun

phos·​phate ˈfäs-ˌfāt 

1

a(1)

: a salt or ester of a phosphoric acid

(2)

: the trivalent anion PO₄³⁻ derived from phosphoric acid H₃PO₄

b

: an organic compound of phosphoric acid in which the acid group is bound to nitrogen or a carboxyl group in a way that permits useful energy to be released (as in metabolism)

2

: an effervescent drink of carbonated water with a small amount of phosphoric acid flavored with fruit syrup

3

: a phosphatic material used for fertilizers

Examples of phosphate in a Sentence

Recent Examples on the Web

More strikingly, scientists recently reported signs of vivianite (an iron phosphate) and greigite (an iron sulfide). —Sharmila Kuthunur, Space.com, 3 Oct. 2025

These spots are concentric reaction fronts – places where chemical and physical reactions occur – enriched in the minerals vivianite, which contains iron phosphate, and greigite, which is made of iron sulfide. —Amy J. Williams, The Conversation, 12 Sep. 2025

The features are likely due to the presence of ferrous iron phosphate and iron sulfide, or the minerals vivianite and greigite, according to the researchers. —Ashley Strickland, CNN Money, 10 Sep. 2025

Perseverance’s measurements suggested the speckles contained the minerals vivianite, an iron phosphate, and greigite, an iron sulfide—and that both formed in close association with organic carbon. —Humberto Basilio, Scientific American, 9 Sep. 2025

Word History

Etymology

French, from acide phosphorique phosphoric acid

First Known Use

1788, in the meaning defined at sense 1a(1)

Phrases Containing phosphate

• ammonium phosphate
• calcium phosphate
• creatine phosphate
• diammonium phosphate
• disodium phosphate
• glucose phosphate
• glucose-6-phosphate dehydrogenase
• nicotinamide adenine dinucleotide phosphate
• phosphate rock
• trisodium phosphate

Rhymes for phosphate

• bisphosphate
• diphosphate
• triphosphate
• glycerophosphate
• organophosphate
• metaphosphate
• monophosphate
• orthophosphate
• polyphosphate
• pyrophosphate
• superphosphate

Kids Definition

phosphate

noun

phos·​phate ˈfäs-ˌfāt 

1

: a salt of a phosphoric acid

2

: a drink made of carbonated water and fruit syrup with a little phosphoric acid added for tang

Medical Definition

phosphate

noun

phos·​phate ˈfäs-ˌfāt 

1

a

: a salt or ester of a phosphoric acid

b

: the trivalent anion PO₄³⁻ derived from phosphoric acid H₃PO₄

2

: an organic compound of phosphoric acid in which the acid group is bound to nitrogen or a carboxyl group in a way that permits useful energy to be released (as in metabolism)