from
The Collaborative International Dictionary of English v.0.48
Isthmus \Isth"mus\ (?; 277), n.; pl. {Isthmuses}. [L. isthmus,
Gr. 'isqmo`s a neck, a neck of land between two seas, an
isthmus, especially the Isthmus of Corinth; prob. from the
root of 'ie`nai to go; cf. Icel. ei[eth] isthmus. See
{Issue}.] (Geog.)
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.
[1913 Webster]
{Isthmus of the fauces}. (Anat.) See {Fauces}.
[1913 Webster]