Definition of isthmus in English:


Line breaks: isth|mus
Pronunciation: /ˈɪsθməs
, ˈɪstməs
, ˈɪsməs

noun (plural isthmuses)

1A narrow strip of land with sea on either side, forming a link between two larger areas of land.
More example sentences
  • Land routes are really old, especially through isthmuses.
  • The British arrived almost a century ago to build the railroad that slices across the isthmus, linking the Gulf of Mexico to the Pacific Ocean.
  • Only one study to date has used calibration points from the fossil record to estimate the divergence of sister species distributed on both sides of the isthmus.
2 (plural isthmi) Anatomy A narrow organ, passage, or piece of tissue connecting two larger parts.
More example sentences
  • Thoracic aortic injuries most often occur at the aortic isthmus in the majority of the cases.
  • It has 2 lobes, called the right lobe and the left lobe, joined by a narrow isthmus.
  • The cervix forms the lower third, connected by a narrow isthmus to the main muscular body of the uterus.


mid 16th century: via Latin from Greek isthmos.

Definition of isthmus in: