An isthmus is a narrow strip of land, bordered on two sides by water, and connects two larger land masses. The term is pronounced “IS-mus” with a silent th. The plural form can either be isthmuses or isthmi.
The most famous isthmus is Panama, which connects the North and South American continents. Other isthmuses include:
Isthmuses are the duals of straits. That is, while isthmuses lie between two bodies of water and joins two larger land masses, straits lie between two land masses and connects two larger bodies of water.