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. | 1. | a narrow strip of land, bordered on both sides by water, connecting two larger bodies of land. |
| 2. | Anatomy, Zoology. a connecting, usually narrow, part, organ, or passage, esp. when joining structures or cavities larger than itself. |
| 3. | Ichthyology. the narrow fleshy area between the sides of the lower jaw of a fish. |

A narrow strip of land that connects two larger bodies of land and has water on both sides.
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.
isthmus
narrow strip of land connecting two large land areas otherwise separated by the sea. Unquestionably the two most famous are the Isthmus of Panama, connecting North and South America, and the Isthmus of Suez, connecting Africa and Asia. Historically the Isthmus of Corinth was of major importance because it connected what otherwise would be the island of the Peloponnese with the rest of the Greek peninsula. Isthmuses are of great importance in plant and animal geography because they offer a path for the migration of land plants and animals between the two land masses they connect.
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