atoll

American  

[at-awl, -ol, -ohl, uh-tawl, uh-tol, uh-tohl] / ˈæt ɔl, -ɒl, -oʊl, əˈtɔl, əˈtɒl, əˈtoʊl /

noun

1. a ring-shaped coral reef or a string of closely spaced small coral islands, enclosing or nearly enclosing a shallow lagoon.

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atoll British  

/ əˈtɒl, ˈætɒl /

noun

1. a circular coral reef or string of coral islands surrounding a lagoon

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Etymology

Origin of atoll

First recorded in 1615–25; earlier atollon, from French: a word used in early descriptions of the Maldive Island atolls; said to be Divehi ( Indo-Aryan language of the Maldives) atoḷu

Explanation

An atoll is an island formed by a ring-shaped coral reef encircling a lagoon. The word comes from the language of the Maldives, an island chain in the Indian Ocean famous for gorgeous beaches and coral reefs. The word atoll appeared in English in the early 17th century, when the British and the Dutch were vying for control of Indian Ocean trade. You may have heard of Bikini Atoll, in the South Pacific — where the U.S. did extensive nuclear testing in the 1940s and 1950s. Its people were moved to neighboring atolls but haven’t been able to return because of lingering radiation. Even so, Bikini Atoll has become a destination for divers interested in WWII shipwrecks.

Example Sentences

Hughes pointed to the impact of the United States' 15-megaton Bravo test at Bikini Atoll in the Marshall Islands on March 1, 1954 -- "equivalent to 1,000 Hiroshima bombs -- an absolute monstrosity".

From Barron's • Jan. 22, 2026

For years, historians followed the bomb’s echoes through the Cold War: Bikini Atoll and nuclear bunkers, Strangelove and SALT, détente and Defcon, Star Wars and saber rattling, to hit a few low points.

From The Wall Street Journal • Jan. 16, 2026

France paid New Zealand $7 million, and New Zealand agreed to deport the spies to Hao Atoll in French Polynesia, where they were to spend three years on a military base.

From Slate • Jul. 22, 2025

The next oldest albatross that researchers are aware of at Midway Atoll is about 45 years old, he said.

From New York Times • Dec. 6, 2024

To the west, about eighty miles, was Bikini Atoll, a group of small coral islands.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

Related Words

• isle
• reef