1. a narrow strip of land connecting two larger land areas
Usage: geography
2. a narrow connecting part between two larger structures
Usage: anatomy; technical

Examples

• The Isthmus of Panama connects North and South America.
• The Panama Canal was built across the narrow isthmus.
• Central America forms an isthmus between two continents.
• The isthmus was only a few miles wide at its narrowest point.
• Ancient traders crossed the isthmus to reach the other sea.
• The thyroid isthmus connects the two lobes of the gland.