isthmos

Isthmos (Greek: ἰσθμός) is the term from which the English isthmus is derived. In geography, an isthmos refers to a narrow strip of land that connects two larger landmasses and separates two bodies of water. The word originates from the Greek ἰσθμός, meaning neck, narrow pass, or bridge.

In practice, an isthmos is a land bridge that links two continental areas while separating two seas or other bodies of water on either side. It contrasts with a strait, which is a water passage that links two bodies of water but lies between lands. Isthmi commonly form through a combination of sediment deposition and tectonic movements; sea-level changes can also play a role in exposing land that later becomes an isthmus. They may function as natural routes for overland travel and, where a canal is constructed, as vital maritime shortcuts.

Notable examples include the Isthmus of Panama, linking North and South America and hosting the Panama Canal; the Isthmus of Suez, connecting Africa and Asia and enclosing the Suez Canal; and the Isthmus of Corinth in Greece, which historically connected the Greek mainland with the Peloponnese.

Historically, isthmuses have been strategically important for trade, defense, and migration, and the term is used in various scientific and cultural contexts, including the Isthmian Games named after the Corinthian isthmus.