Tombolo

noun - A tombolo is a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. Several islands tied together by bars which rise above the water level are called a tombolo cluster. Two or more tombolos may form an enclosure (called a lagoon) that can eventually fill with sediment.

Origin

From the Italian tombolo, derived from the Latin tumulus, meaning 'mound', and sometimes translated as ayre.