Jump To:

• phosphorus
  phosphorus

  noun

  a solid, nonmetallic element existing in at least three allotropic forms, one that is yellow, poisonous, flammable, and luminous in the dark, one that is red, less poisonous, and less flammable, and another that is black, insoluble in most solvents, and the least flammable. The element is used in forming smoke screens, its compounds are used in matches and phosphate fertilizers, and it is a necessary constituent of plant and animal life in bones, nerves, and embryos. P; 30.974; 15; (yellow) 1.82 at 20°C, (red) 2.20 at 20°C, (black) 2.25–2.69 at 20°C.
• Phosphorus
  Phosphorus

  noun

  Phosphor.

phosphorus

¹ American  

[fos-fer-uhs] / ˈfɒs fər əs /

noun

• phosphori
  plural

1. Chemistry. a solid, nonmetallic element existing in at least three allotropic forms, one that is yellow, poisonous, flammable, and luminous in the dark, one that is red, less poisonous, and less flammable, and another that is black, insoluble in most solvents, and the least flammable. The element is used in forming smoke screens, its compounds are used in matches and phosphate fertilizers, and it is a necessary constituent of plant and animal life in bones, nerves, and embryos. P; 30.974; 15; (yellow) 1.82 at 20°C, (red) 2.20 at 20°C, (black) 2.25–2.69 at 20°C.

2. any phosphorescent substance.

3. phosphor.

---

Phosphorus ² American  

[fos-fer-uhs] / ˈfɒs fər əs /

noun

1. Phosphor.

---

Phosphorus ¹ British  

/ ˈfɒsfərəs /

noun

1. a morning star, esp Venus

---

phosphorus ² British  

/ ˈfɒsfərəs /

noun

1. an allotropic nonmetallic element occurring in phosphates and living matter. Ordinary phosphorus is a toxic flammable phosphorescent white solid; the red form is less reactive and nontoxic: used in matches, pesticides, and alloys. The radioisotope phosphorus-32 ( radiophosphorus ), with a half-life of 14.3 days, is used in radiotherapy and as a tracer. Symbol: P; atomic no: 15; atomic wt: 30.973 762; valency: 3 or 5; relative density: 1.82 (white), 2.20 (red); melting pt: 44.1°C (white); boiling pt: 280°C (white)

2. a less common name for a phosphor

---

phosphorus Scientific  

/ fŏs′fər-əs /

1. A highly reactive, poisonous nonmetallic element occurring naturally in phosphates, especially in the mineral apatite. It exists in white (or sometimes yellow), red, and black forms, and is an essential component of protoplasm. Phosphorus is used to make matches, fireworks, and fertilizers and to protect metal surfaces from corrosion. Atomic number 15; atomic weight 30.9738; melting point (white) 44.1°C; boiling point 280°C; specific gravity (white) 1.82; valence 3, 5.

2. See Periodic Table

---

Other Word Forms

Noun Inflected Forms

• phosphori
  plural

---

Etymology

Origin of phosphorus

1620–30; < New Latin phōsphorus phosphorus; Latin: morning star; see Phosphor

---

Example Sentences

See Examples For:

phosphorus Phosphorus phosphori

They accomplished this by dissolving different mineral components one at a time, allowing them to distinguish phosphorus that had been available for biological activity from phosphorus locked away in mineral structures.

From Science Daily ● Oct. 12, 2026

The researchers addressed this limitation by separating phosphorus according to the minerals that contained it.

From Science Daily ● Oct. 12, 2026

A Navy MK25 phosphorus location marker is used to create a visible smoke and flame signal to locate objects or people in the water.

From Los Angeles Times ● Sep. 29, 2026

Even so, its concentration showed strong relationships with several important soil properties, including pH, microbial biomass phosphorus, organic matter content, and phosphorus dissolved in soil water.

From Science Daily ● Sep. 27, 2026

It was largely because of this mastery of phosphorus that Sweden became, and remains, a leading producer of matches.

From "A Short History of Nearly Everything" by Bill Bryson

Phosphorus - found in fertiliser and processed livestock feed - is considered to be one of the substances of most concern.

From BBC ● Jul. 22, 2026

Phosphorus helps transport energy within plant cells and is critical for early root growth and the formation of seeds and fruit.

From Salon ● Apr. 8, 2026

Phosphorus plays an essential role in various biological processes, like creating DNA structure and facilitating the energy transfer between cells, Li explained.

From Science Daily ● Nov. 18, 2024

Phosphorus is naturally occurring but can also come from agricultural runoff, leaky septic systems, stormwater drainage and other human activities.

From Los Angeles Times ● May 8, 2024

“It really is a bit too thick,” the Head Mistress of Eton was saying to the Director of Crematoria and Phosphorus Reclamation.

From "Brave New World" by Aldous Huxley

A chandelier of this blue metal was pendant from the ceiling, and in its cup-like extremities, arranged in vertical tiers, were round balls of the phosphori, glowing softly.

From The Certainty of a Future Life in Mars by L. P. Gratacap

At first a glow covered the sides of the houses, the colonnade and dome, while the glass prisms above them sent out rays from their imprisoned balls of phosphori.

From The Certainty of a Future Life in Mars by L. P. Gratacap

Around the room were alcoves lit by lamps of the phosphori, and in each alcove a globe of a blue metal upon which were painted sketches like charts or maps.

From The Certainty of a Future Life in Mars by L. P. Gratacap

It is indeed a phosphori as, if I recall it aright, the sulphides of barium, strontium, and calcium were upon our earth.

From The Certainty of a Future Life in Mars by L. P. Gratacap

It was illuminated by balls of phosphori in glass globes, and its cool, broad halls and stairways were, in the soft light, very beautiful.

From The Certainty of a Future Life in Mars by L. P. Gratacap

Random Word

Spin the wheel and learn a new word!

---