D defs.my
Entry 1 sense Webster, 1913

Isthmus

/ĭs'-məs/ · Isth·mus · IPA /ˈɪs.məs/
01 n. A neck or narrow slip of land by which two continents are connected, or by which a peninsula is united to the mainland; as, the Isthmus of …
pl. Isthmuses ((#))
  1. 1.
    A neck or narrow slip of land by which two continents are connected, or by which a peninsula is united to the mainland; as, the Isthmus of Panama; the Isthmus of Suez, etc.(Geog.)
Phrases & compounds
Isthmus of the fauces — See Fauces.