Barrier Island Definition

A long, relatively narrow island running parallel to the mainland, built up by the action of waves and currents and serving to protect the coast from erosion by surf and tidal surges.

A long, narrow island, parallel to the coastline, formed from deposits of sand and sediment thrown up by the waves, that serves the shore as a protective barrier against tidal waves, storms, etc.

A long, narrow sand island that is parallel to the mainland and serves to protect the coast from erosion. Barrier islands typically have dunes along the exposed outer side, zones of vegetation in the interior, and swampy areas along the inner lagoon.