phosphorus
noun
phos·pho·rus
ˈfäs-f(ə-)rəs 
often attributive
1
: a phosphorescent substance or body
especially
: one that shines or glows in the dark
2
or less commonly phosphorous
: 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
The remaining elements include phosphorus, potassium, and nitrogen, which are key ingredients in fertilizers, according to researchers.
—
Prabhat Ranjan Mishra, Interesting Engineering, 23 Oct. 2025
Since orange trees are heavy feeders, look for a fertilizer that contains more nitrogen, such as a 2-1-1 or 3-1-1 nitrogen-phosphorus-potassium (NPK) ratio, as well as micro nutrients like magnesium, zinc, and iron.
—Karen Brewer Grossman, Southern Living, 22 Oct. 2025
The build-up of phosphorus in the watershed's soil would take decades to deplete even if all litter application there stopped, according to court testimony.
—Arkansas Online, 21 Oct. 2025
Minerals in butter, like calcium, magnesium, phosphorus, and potassium, play roles in bone strength, muscle function, and heart health.
—Brittany Lubeck, Verywell Health, 21 Oct. 2025
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Prabhat Ranjan Mishra, Interesting Engineering, 23 Oct. 2025
Since orange trees are heavy feeders, look for a fertilizer that contains more nitrogen, such as a 2-1-1 or 3-1-1 nitrogen-phosphorus-potassium (NPK) ratio, as well as micro nutrients like magnesium, zinc, and iron.
—Karen Brewer Grossman, Southern Living, 22 Oct. 2025
The build-up of phosphorus in the watershed's soil would take decades to deplete even if all litter application there stopped, according to court testimony.
—Arkansas Online, 21 Oct. 2025
Minerals in butter, like calcium, magnesium, phosphorus, and potassium, play roles in bone strength, muscle function, and heart health.
—Brittany Lubeck, Verywell Health, 21 Oct. 2025
See All Example Sentences for phosphorus
Cite this Entry
“Phosphorus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/phosphorus. Accessed 31 Oct. 2025.
Copy CitationKids Definition
phosphorus
noun
phos·pho·rus
ˈfäs-f(ə-)rəs
1
: a phosphorescent substance
especially
: one that glows in the dark
2
: a nonmetallic element that occurs widely especially as phosphates see element
phosphoric
adjective
fäs-ˈfȯr-ik
-ˈfär-
phosphorous
adjective
ˈfäs-f(ə-)rəs;
fäs-ˈfōr-əs
-ˈfȯr-
Medical Definition
phosphorus
noun
phos·pho·rus
ˈfäs-f(ə-)rəs
often attributive
: 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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