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
Cite this Entry
“Phosphorus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/phosphorus. Accessed 1 Nov. 2026.
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