■ An exclave
A detached piece of one administrative region completely surrounded by at least one other region.
This is much easier to understand from the example, a photograph of part of a map of 葛生町（くずうまち） in 栃木県（とちぎけん）. Just under the sheep's nose is an "island" labelled 葛生町飛地, which means that it is a part of 葛生 but is completely surrounded by 栃木市. (Actually it is cut off only by a curious narrow strip along the river.)
The English term "exclave" is somewhat obscure, and tends to be used mostly by individuals with a passionate interest in exclaves. At least in Britain, a common notation on maps is simply "detached" (or "Det."), as in the case of the hundred of Maelor, a lump of Flintshire which used to be completely surrounded by Cheshire, Shropshire, and Denbighshire.
This entry was created by Brian Chandler.