An isthmus (narrow strip of land).
Via Latin isthmus, from Ancient Greek ἰσθμός (isthmos, “neck”). Cognate to Old Norse eið (“isthmus”).
isthmus (plural isthmuses or rare isthmi)
- A narrow strip of land, bordered on both sides by water, and connecting two larger landmasses.
- (anatomy) Any such narrow part connecting two larger structures.
Derived terms 
External links 
isthmus (genitive isthmī); m, second declension
Usage notes 
- Capitalised, it refers to the Isthmus of Corinth.