[is-muh s] /ˈɪs məs/

noun, plural isthmuses, isthmi
[is-mahy] /ˈɪs maɪ/ (Show IPA)
a narrow strip of land, bordered on both sides by water, connecting two larger bodies of land.
Anatomy, Zoology. a connecting, usually narrow, part, organ, or passage, especially when joining structures or cavities larger than itself.
Ichthyology. the narrow fleshy area between the sides of the lower jaw of a fish.
noun (pl) -muses, -mi (-maɪ)
a narrow strip of land connecting two relatively large land areas


1550s, from Latin isthmus, from Greek isthmos “narrow passage, narrow neck of land,” especially that of Corinth, of unknown origin, perhaps from eimi “to go” + suffix -thmo (cf. ithma “a step, movement”).

isthmus isth·mus (ĭs’məs)
n. pl. isth·mus·es or isth·mi (-mī’)
A constriction or narrow passage connecting two larger parts of an organ or other anatomical structure.
Plural isthmuses or isthmi (ĭs’mī’)
A narrow strip of land connecting two larger masses of land.
isthmus [(is-muhs)]

A narrow strip of land that connects two larger bodies of land and has water on both sides.


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