/ Dictionary / Index A atoll: Meaning and Definition of Find definitions for: at•oll Pronunciation: (at'ôl, -ol, -ōl, u-tôl', u-tol', u-tōl'), [key] — n. a ring-shaped coral reef or a string of closely spaced small coral islands, enclosing or nearly enclosing a shallow lagoon. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: atoll (Thesaurus) at. no. atom Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language