Islet
An islet is a very small island.
Types
As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability.
Rock – A "rock", in the sense of a type of islet, is an uninhabited landform composed of rock, lying offshore, and having at most minimal vegetation.
Sandbar – An exposed sandbar is another type of islet.
Sea stack – A thin, vertical landform jutting out of a body of water.
Skerry – A small rocky island, usually defined to be too small for habitation.
Subsidiary islets – A more technical application is to small land features, isolated by water, lying off the shore of a larger island. Likewise, any emergent land in an atoll is also called an islet.
Tidal island – Often small islands (not necessarily always islets) which lie off the mainland of an area, being connected to it in low tide and isolated in high tide.
River island – A small islet within the current of a river.