Isthmus
Etymology
From Greek "isthmos" ("neck, narrow passage"). The ancient Isthmus of Corinth gave the word its geographic sense.
noun · /IS-muhs/
A narrow strip of land connecting two larger landmasses, with water on either side.
What it names
The slender land-bridge — a landform with outsized strategic and economic importance, as at Panama.
Example
The canal was cut across the narrow isthmus to join the two oceans.
Related idea
An isthmus joins land through water; an archipelago is the opposite pattern — land broken into many scattered islands.
See also