Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, such as the Philippines.
Geography of Long Island
In United States v. Maine (1985) the U.S. Supreme Court treated the island as a peninsula for the purposes of a boundary decision. Despite the legal decision the United States Board on Geographic Names considers Long Island an island, because it is surrounded by water.