noun

The word "atoll" means a ring-shaped coral reef enclosing a lagoon, especially one with no central island. Atolls are typically formed by the growth of coral organisms in shallow ocean waters, and the islands or rocks that make up the atoll are usually arranged in a ring around the lagoon.

Example

1. The islanders lived peacefully on the atoll for generations.
2. The atoll was surrounded by crystal clear waters and white sand beaches.
3. The boat stopped at the atoll to take on more supplies.