noun Download 🔗Share A type of island consisting of a ribbon reef that nearly or entirely surrounds a lagoon and supports, in most cases, one to many islets on the reef platform. Atolls have a unique geology, so not all islands with a reef and a lagoon are atolls Examples : "The airplane flew over a beautiful atoll, a ring of small islands surrounding a calm, blue lagoon. " geology geography environment nature ocean Chat with AIVocabulary GamePractice Reading