English Reference

Word

phosphorus

Phoneticsphos·pho·rus

US/ˈfɑsfɝəs/

UK/fˈɒsfɔːɹəs/

Definitions

01chemical element

B2 · Science

n. a chemical element that is important for plants and animals to grow; it is also used to make matches and fertilizers.

n. a nonmetallic chemical element of the nitrogen family that is essential for biological processes and widely used in industrial applications.

“Farmers add phosphorus to the soil to help their crops grow stronger.”

“White phosphorus is highly reactive and spontaneously ignites upon exposure to air, necessitating storage under water or an inert atmosphere.”

Technical

Usage

Uncountable when referring to the element itself; countable when referring to specific allotropic forms or chemical varieties.

Synonyms

P

02glowing substance

C2 · Science

n. any substance that glows in the dark after being exposed to light.

n. any substance exhibiting phosphorescence; a phosphor.

“The old scientist studied a piece of phosphorus that glowed with a faint green light.”

“In early chemical texts, the term phosphorus was applied broadly to various materials that emitted light without heat.”

Archaic · Technical

Teaching tip

In modern English, 'phosphor' is the standard term for substances that glow in electronics; 'phosphorus' is reserved for the specific element.

Synonyms

phosphor

03the morning star

C2

n. an ancient name for the planet Venus when it appears in the sky before the sun rises.

n. the personification of the morning star in Greek mythology; the planet Venus appearing in the eastern sky before sunrise.

“The poet looked up at Phosphorus shining brightly in the early morning sky.”

“Classical literature often contrasts Phosphorus, the bringer of light, with Hesperus, the star of the evening.”

Literary · Archaic

Synonyms

Lucifermorning star

Antonyms

Hesperus

Real-World Examples

“Pesticides and fertilizers go together in avocado production, so we believe the pesticide reduction made each extra unit of fertilizer less worthwhile, leading growers to apply less nitrogen and phosphorus.”
The Conversation · 29 Jul 2026
“An algal bloom caused by eutrophication, when an ecosystem is overloaded with nutrients like phosphorus.”
Smithsonian Magazine · 17 Jun 2016
“The United States could exhaust its domestic phosphorus supply within 40 years.”
Phys.org · 14 Aug 2026

Etymology

From Latinised Greek Phosphorus, from Ancient Greek Φωσφόρος (Phōsphóros, “the bearer of light”), from φῶς (phôs, “light”) + φέρω (phérō, “I bear, carry”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Related words

Domain

Chemistry

This entry

Level
C1 · Advanced
Frequency
Frequent
Updated

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English Reference