isthmus

American  

[is-muhs] / ˈɪs məs /

noun

isthmuses, plural isthmi plural

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, especially when joining structures or cavities larger than itself.

3. Ichthyology. the narrow fleshy area between the sides of the lower jaw of a fish.

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isthmus British  

/ ˈɪsməs /

noun

1. a narrow strip of land connecting two relatively large land areas

2. anatomy

   1. a narrow band of tissue connecting two larger parts of a structure

   2. a narrow passage connecting two cavities

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isthmus Scientific  

/ ĭs′məs /

isthmuses plural

1. A narrow strip of land connecting two larger masses of land.

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isthmus Cultural  

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

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Other Word Forms

• isthmoid
  adjective

Etymology

Origin of isthmus

1545–55; < Latin < Greek isthmós neck (of land)

Explanation

An isthmus is a land bridge, a narrow strip of land that stretches across a body of water to connect two larger land masses. The Greek isthmos means "neck," so you can see how isthmus came to mean the connecting strip between land masses. If you look at an example, say the Isthmus of Panama, you can see how that neck-like bit of land separates the Caribbean Sea from the North Pacific Ocean as it connects North and South America. Think of an isthmus as kind of like a turkey neck that connects the bird's body and head (at least until Thanksgiving).

Example Sentences

Roosevelt was intrigued by the military and commercial possibilities of a canal across the isthmus, cutting 8,000 miles off a New York-San Francisco voyage.

From Barron's • Jan. 18, 2026

Paterson persuaded the Scottish parliament to establish a new enterprise based on England’s East India Company to found a Scottish colony on the narrow isthmus joining North and South America.

From The Wall Street Journal • Nov. 30, 2025

The waterway was cleaved across the most narrow section of the Panamanian isthmus in the late 1800s and early 1900s, by French and then U.S. engineers.

From Los Angeles Times • Jan. 31, 2025

The migrant route through the narrow isthmus grew exponentially in popularity in recent years with the help of organized crime in Colombia, making it an affordable, if dangerous, land route for hundreds of thousands.

From Seattle Times • May 10, 2024

The isthmus is a medley of mountains, beaches, wet tropical forests, and dry savannas, and is the most ecologically diverse area in Mesoamerica.

From "1491" by Charles C. Mann

Related Words

• collar