Why is Central America considered an isthmus?

Central America is considered an isthmus because it is a narrow strip of land that connects two larger landmasses—in this case, North America and South America—while separating two bodies of water, the Pacific Ocean and the Caribbean Sea.12

Geographically, Central America forms the tapering land bridge that extends from the Isthmus of Tehuantepec in the north to the Isthmus of Panama in the south. This region is characterized by its narrow width; at its most constricted point, it is only about 30 miles (50 km) wide, and no location within the region is more than 125 miles (200 km) from the sea. Beyond its role as a physical connector, the region has historically served as a vital corridor for the migration of plants, animals, and humans between the two continents.1342