pentagon

1 of 2

noun (1)

pen·​ta·​gon ˈpen-tə-ˌgän 

: a polygon of five angles and five sides

Pentagon

2 of 2

noun (2)

: the U.S. military leadership

Examples of pentagon in a Sentence

Noun (1)

The general attended a meeting at the Pentagon.

There was disagreement between the President and the Pentagon over the new military budget.

Recent Examples on the Web

Noun

Conservative conspiracy theories swirled last year that Swift was part of a Pentagon plot fueled by Democrats to sway the 2024 election. —Francesca Chambers, USA Today, 27 Aug. 2025

Pentagon leadership has expressed concerns about losing access to military bandwidth, while telecom industry analysts have grown concerned that companies are overextending themselves in the gold rush. —Rohan Goswami, semafor.com, 26 Aug. 2025

Noun

This happens often enough when one administration succeeds another, to be sure, with the new team insisting that its predecessors were idiots, but the Hegseth Pentagon carries such insults to a new level. —Eliot A. Cohen, The Atlantic, 29 Jan. 2026

Just earlier this year, defense secretary Pete Hegseth revealed that Musk’s AI chatbot Grok will be operating inside Pentagon networks. —Victor Tangermann, Futurism, 29 Jan. 2026

Word History

Etymology

Noun (1)

Greek pentagōnon, from neuter of pentagōnos pentagonal, from penta- + gōnia angle — more at -gon

Noun (2)

the Pentagon building, headquarters of the Department of Defense

First Known Use

Noun (1)

1570, in the meaning defined above

Noun (2)

1945, in the meaning defined above

Phrases Containing pentagon

• the Pentagon

Rhymes for pentagon

• aileron
• antiphon
• autobahn
• carillon
• castellan
• celadon
• cephalon
• chitosan
• cynodon
• denouement
• deuteron
• echelon

Kids Definition

pentagon

noun

pen·​ta·​gon ˈpent-ə-ˌgän 

: a polygon of five angles and five sides