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.
Terminology of the British Isles
The dictionary definition of British Isles is that it is a geographical term that refers to the whole of Ireland and Great Britain as well as the surrounding islands. It is sometimes incorrectly used as if identical to the UK; or to refer to Great Britain and the surrounding islands, excluding the island of Ireland entirely. The BBC and "The Times" have style guides that mandate the dictionary definition but occasional misuse can be found on their web sites.