# atoll

/ˈæˌtɑɫ/ (US) · /ˈætɒl/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/atoll
Updated: 2026-05-20

## Definition

a ring-shaped island made of coral that forms around a lagoon. It is usually found in the ocean and is surrounded by water.

For teachers: a ring-shaped coral island or reef, typically surrounding a lagoon. Formed by the growth of coral on the rim of a volcanic crater or on the edge of a submerged island.

## Examples

- The island is a small atoll in the middle of the ocean.
- Many of the islands in the Pacific are actually atolls formed by coral reefs over thousands of years.
- The unique ecosystem of the atoll is maintained by the delicate balance between the coral reef and the surrounding lagoon, which provides a protected habitat for various marine species.

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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.