# sulfur

/ˈsəɫfɝ/ (US) · /sˈʌlfɜː/ (UK)

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

## Senses

### 1. chemical element

noun · CEFR B2 · Technical

a bright yellow chemical element that smells like rotten eggs when it is part of a compound or burned.

For teachers: a multivalent non-metallic chemical element, atomic number 16, which is essential for life and used industrially in the production of sulfuric acid and gunpowder.

- The hot springs gave off a strong smell of sulfur that filled the valley.
- Sulfur is a key component in the vulcanization of rubber, a process that significantly enhances the material's durability and heat resistance.

Usage: Uncountable when referring to the chemical element.

### 2. a type of butterfly

noun · CEFR C2 · Technical

a type of butterfly that is usually bright yellow or greenish-yellow.

For teachers: any of various pierid butterflies belonging to the subfamily Coliadinae, characterized by their distinct yellow or orange wings.

- We saw a bright yellow sulfur landing on the flowers in the garden.
- The clouded sulfur is a common sight in North American clover fields during the mid-summer months.

Usage: Countable in this biological sense.

### 3. yellow-green color

adjective · CEFR C1 · Literary

having a pale, yellowish-green color like the element sulfur.

For teachers: denoting a specific pale yellowish-green hue resembling the natural appearance of elemental sulfur.

- The sky turned a strange sulfur color just before the storm began.
- The artist used sulfur highlights to create a sickly, atmospheric glow across the stagnant pond in the painting.

### 4. to treat with sulfur

verb · CEFR C2 · Technical

to use sulfur to clean something or to keep pests away from plants.

For teachers: to treat, fumigate, or preserve a substance or plant by applying sulfur or sulfur dioxide.

- The farmer decided to sulfur the vines to protect them from fungus.
- Traditional winemakers sometimes sulfur the oak barrels to prevent the growth of unwanted bacteria before storage.

Usage: Transitive verb taking a direct object.

## Examples

- Sulfur is a bright yellow mineral found near volcanoes.
- The match head contains sulfur, which helps it ignite when you strike it against a rough surface.
- In the early industrial era, the high sulfur content in coal led to significant atmospheric pollution, eventually resulting in the phenomenon known as acid rain.

---

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.