coral reef

American  

noun

• coral reefs
  plural

1. a reef composed mainly of coral and other organic matter of which parts have solidified into limestone.

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coral reef British  

noun

1. a marine ridge or reef consisting of coral and other organic material consolidated into limestone

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coral reef Scientific  

1. A mound or ridge of living coral, coral skeletons, and calcium carbonate deposits from other organisms such as calcareous algae, mollusks, and protozoans. Most coral reefs form in warm, shallow sea waters and rise to or near the surface, generally in the form of a barrier reef, fringing reef, or atoll. Coral reefs grow upward from the sea floor as the polyps of new corals cement themselves to the skeletons of those below and in turn provide support for algae and other organisms whose secretions serve to bind the skeletons together. The resulting structure provides a critical habitat for a wide variety of fish and marine invertebrates. Coral reefs also protect shores against erosion by causing large waves to break and lose some of their force before reaching land. The Great Barrier Reef off the northeastern coast of Australia extends for some 2,000 km (1,240 mi), making it the world's largest coral reef.

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coral reef Cultural  

1. A formation, at or near the surface of tropical waters, formed by skeletal deposits of corals, a form of sea life.

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Discover More

Atolls — ring-shaped islands that nearly or entirely enclose a lagoon — are coral reefs.

Coral reefs form a protective environment for a wide variety of marine animals.

Coral reefs are very sensitive to chemical pollution and changes in temperature and are considered to be in danger from environmental stress.

The largest coral reef is the Great Barrier Reef of Australia.

Other Word Forms

Noun Inflected Forms

• coral reefs
  plural

Etymology

Origin of coral reef

First recorded in 1735–45

Example Sentences

See Examples For:

coral reef

Environmental experts say the spill threatens wildlife, protected ecosystems and fishing communities around Qeshm, which is home to mangrove forests, nearby coral reef habitats and nesting sites for critically endangered Hawksbill turtles.

From BBC ● Aug. 14, 2026

To reach these conclusions, researchers analyzed data from coral reef regions around the world.

From Science Daily ● Jan. 4, 2026

She compares the human body to a coral reef, where animals, plants, and microscopic organisms “cohabitate as one huge and beautiful chimeric metaorganism.”

From The Wall Street Journal ● Nov. 4, 2025

A coral reef is normally built out of lots of colonies of different kinds.

From NewsForKids.net ● Nov. 27, 2024

In the water, the rocks form a crescent shape that calms the waves and forms a coral reef perfect for snorkeling.

From "Everything, Everything" by Nicola Yoon

Related Words

• atoll
• beach
• shoal