Atoll (noun)

A coral island consisting of a reef surrounding a lagoon.

Origin:

From the dhivehi word "atholhu" meaning "island".

Examples:

1. The Maldives is a chain of atolls in the Indian Ocean.
2. The atoll is home to a diverse array of marine life.
3. The atoll is a popular destination for scuba divers.
4. The island was formed by the coral reef growing around a volcanic island.
5. The atoll was nearly destroyed by the tsunami.