From Longman Dictionary of Contemporary Englishatollat‧oll /ˈætɒl $ ˈætɒːl, ˈætɑːl/ noun [countable] SGa coral island in the shape of a ring
Examples from the Corpus
atoll• When the island had sunk beneath the waves the former fringe would be left as an atoll.• Barrier reefs and atolls are very like each other in general form and zonation.• Even certain elevated atolls seem to have such a thickness of limestone as to indicate subsidence before present uplift.• We continued along the north coast of West Spitsbergen, with a detour to the little atoll of Moffen Island.• It is incontrovertible that there has been long-continued subsidence on many oceanic atolls.• This is only well developed on the seaward side of the windward reef of atolls.• In between is a minefield of smaller idyllic coconut and white sand atolls.• In 1995 he sailed into the Moruroa test zone and hid on the atoll to frustrate the underground tests.Origin atoll (1600-1700) Maldivian atolu 