pentagon

American  

[pen-tuh-gon, -guhn] / ˈpɛn təˌgɒn, -gən /

noun

1. a polygon having five angles and five sides.

2. the Pentagon,

   1. a building in Arlington, Virginia, having a plan in the form of a regular pentagon, containing most U.S. Defense Department offices.

   2. the U.S. Department of Defense; the U.S. military establishment.

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pentagon ¹ British  

/ ˈpɛntəˌɡɒn, pɛnˈtæɡənəl /

noun

1. a polygon having five sides

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Pentagon ² British  

/ ˈpɛntəˌɡɒn /

noun

1. the five-sided building in Arlington, Virginia, that houses the headquarters of the US Department of Defense

2. the military leadership of the US

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pentagon Scientific  

/ pĕn′tə-gŏn′ /

1. A polygon having five sides.

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Pentagon ¹ Cultural  

1. An immense five-sided building in Virginia, just outside Washington, D.C., that serves as headquarters for the Department of Defense.

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pentagon ² Cultural  

1. A polygon having five sides.

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Discover More

The term is often used to refer to the Department of Defense or the military: “The Pentagon agreed today to submit the modified weapons plan to the president.”

The Pentagon was severely damaged by the September 11 attacks.

The Pentagon is a huge five-sided building near Washington, D.C., that contains offices of the Department of Defense.

Other Word Forms

• pentagonal adjective
• pentagonally adverb
• subpentagonal adjective

Etymology

Origin of pentagon

1560–70; < Late Latin pentagōnum < Greek pentágōnon, noun use of neuter of pentágōnos five-angled. See penta-, -gon

Example Sentences

Hint: It’s what you get when you subtract a twogon from a pentagon.

From Slate • Feb. 22, 2025

The vision involves developing human capital, the digital economy and inclusivity and sustainability, he said, referring to it as the "pentagon strategy".

From Reuters • Sep. 4, 2023

They could arrange four hat tiles into a hexagonlike structure, two tiles into a pentagon and another combination of two tiles into a parallelogram.

From Scientific American • Apr. 10, 2023

A regular pentagon is inscribed in a circle of radius 12 cm.

From Textbooks • Feb. 13, 2015

Nestled within the lines of the star is a pentagon.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife