isthmus

n. narrow strip of land bordered by water on both sides; (Anatomy) fauces

An isthmus (, , plural isthmuses or isthmi) is a narrow strip of land that is bordered on two sides by water and connects two larger land masses. It is the inverse of a strait (which lies between two land masses and connects two larger bodies of water).Isthmi are naturally good places to build canals. The Panama Canal, for instance, which connects the Atlantic and Pacific Oceans, drastically reduces the naval travel time between the east and west coasts of the Americas.
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Noun
1. a relatively narrow strip of land (with water on both sides) connecting two larger land areas
(hypernym) land, dry land, earth, ground, solid ground, terra firma
(hyponym) Central America
2. a narrow band of tissue connecting two larger parts of an anatomical structure
(hypernym) tissue

n. isthmus, narrow strip of land bordered by water on both sides

(n.)
A neck or narrow slip of land by which two continents are connected, or by which a peninsula is united to the mainland; as, the Isthmus of Panama; the Isthmus of Suez, etc.