noun, often attributive
phos·​pho·​rus | \ ˈfäs-f(ə-)rəs How to pronounce phosphorus (audio) \

Definition of phosphorus

1 : a phosphorescent substance or body especially : one that shines or glows in the dark
2 or less commonly phosphorous \ ˈfäs-​f(ə-​)rəs How to pronounce phosphorus (audio) \ : a nonmetallic element of the nitrogen family with atomic number 15 that occurs widely in combination especially as phosphates, that is essential for life in all known organisms, and that is used especially in fertilizers and organophosphorus compounds — see Chemical Elements Table

Examples of phosphorus in a Sentence

Recent Examples on the Web Fertilizers higher in phosphorus will help with blooming and fruiting. oregonlive, "Early rose pruning could cause dieback, result in re-prune next spring: Ask an expert," 16 Jan. 2021 In that time, the plant produced 22 million tons of phosphorus sludge—which is toxic if absorbed, ingested, or inhaled and explodes upon exposure to air—that was then stored on the Fort Hall Reservation, the present home of the tribal nation. Nick Martin, The New Republic, "Indian Country Refuses to Be Corporate America’s Dumping Ground," 12 Jan. 2021 The hypothesis currently being tested is that people ate vegetables tainted with pesticides made of organic compounds containing phosphorus. Aniruddha Ghosal, Star Tribune, "'Nobody knows': Experts baffled by mystery illness in India," 8 Dec. 2020 Algae thrive on phosphorus; without large influxes of the element, the blooms can’t grow. Tim Folger, National Geographic, "North America’s most valuable resource is at risk," 17 Nov. 2020 Surprisingly, coffee grounds contain about four times more nitrogen than manure and slightly less phosphorus and potassium. Tom Maccubbin,, "Install bougainvilleas now, unless there is a freeze risk," 26 Dec. 2020 After operating for nearly half a century, the plant has created an underground blob of extremely salty, phosphorus-rich water several miles wide. Nicolás Rivero, Quartz, "America’s green energy hopes hinge on propping up aging nuclear plants," 19 Dec. 2020 For the reversible version with black phosphorus, the researchers used two gates, which reinforced the on/off signal. John Timmer, Ars Technica, "Phosphorus equivalent of graphene makes reconfigurable transistors," 13 Dec. 2020 The report identifies multiple ways to improve water quality, such as banning phosphorus-containing fertilizers and limiting toxic sealants used to coat blacktop driveways and parking lots. Suzanne Baker,, "Banning some types of fertilizers and sealants will improve Naperville-area rivers, streams: Sierra Club," 24 Dec. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'phosphorus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of phosphorus

1680, in the meaning defined at sense 1

History and Etymology for phosphorus

New Latin, from Greek phōsphoros light-bearing — more at phosphor

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Time Traveler for phosphorus Time Traveler

The first known use of phosphorus was in 1680

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Statistics for phosphorus

Last Updated

7 Feb 2021

Cite this Entry

“Phosphorus.” Dictionary, Merriam-Webster, Accessed 9 Mar. 2021.

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More Definitions for phosphorus



English Language Learners Definition of phosphorus

chemistry : a poisonous chemical element that glows in the dark and burns when it is touched by air


phos·​pho·​rus | \ ˈfäs-fə-rəs How to pronounce phosphorus (audio) \

Kids Definition of phosphorus

: a white or yellowish waxy chemical element that gives a faint glow in moist air


noun, often attributive
phos·​pho·​rus | \ ˈfäs-f(ə-)rəs How to pronounce phosphorus (audio) \

Medical Definition of phosphorus

: a nonmetallic multivalent element that occurs widely in combined form especially as inorganic phosphates in minerals, soils, natural waters, bones, and teeth and as organic phosphates in all living cells and that exists in several allotropic forms symbol P — see Chemical Elements Table

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More from Merriam-Webster on phosphorus

Nglish: Translation of phosphorus for Spanish Speakers

Britannica English: Translation of phosphorus for Arabic Speakers Encyclopedia article about phosphorus

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