[at-awl, -ol, -ohl, uh-tawl, uh-tol, uh-tohl] 
| 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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a·toll (āt'ôl', -ŏl', ā'tôl', ā'tŏl')  (click for larger image in new window) n. A ringlike coral island and reef that nearly or entirely encloses a lagoon. [Maldivean atolu; probably akin to Sinhalese ätul, interior (from the interior lagoon), probably from Sanskrit *antala-, interior, variant of antara-; see en in Indo-European roots.] |
atoll (āt'ôl', ā'tôl') Pronunciation Key
(click for larger image in new window) A coral island or series of coral islands forming a ring that nearly or entirely encloses a shallow lagoon. Atolls are surrounded by deep ocean water and range in diameter from about 1 km (0.62 mi) to over 100 km (62 mi). They are especially common in the western and central Pacific Ocean and are believed to form along the fringes of underwater volcanoes. Compare barrier reef, fringing reef. |