# phosphorus

/ˈfɑsfɝəs/ (US) · /fˈɒsfɔːɹəs/ (UK)

Source: https://englishreference.com/word/phosphorus
Updated: 2026-08-27

## Senses

### 1. chemical element

noun · CEFR B2 · Technical

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

For teachers: 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.

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

### 2. glowing substance

noun · CEFR C2 · Archaic · Technical

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

For teachers: 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.

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

### 3. the morning star

noun · CEFR C2 · Literary · Archaic

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

For teachers: 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.

## Examples

- Phosphorus is an essential mineral for healthy bones.
- Farmers often add phosphorus to their soil because it helps crops grow strong roots and produce fruit.
- The excessive runoff of phosphorus from agricultural fertilizers into local waterways can lead to harmful algal blooms that deplete oxygen levels and kill aquatic life.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.