Pentagon

//ˈpɛn.təˌɡɑn// name, noun

name, noun ·Uncommon ·Advanced level

Definitions

Noun
  1. 1
    A polygon with five sides and five angles.

    "Imagine a vast sheet of paper on which straight Lines, Triangles, Squares, Pentagons, Hexagons, and other figures, instead of remaining fixed in their places, move freely about, […]"

  2. 2
    the United States military establishment wordnet
  3. 3
    A fort with five bastions.
  4. 4
    a five-sided polygon wordnet
Proper Noun
  1. 1
    The headquarters of the United States Department of Defense.
  2. 2
    The United States Department of Defense. metonymically

    "The Vietnamese people inspired youth of all nationalities […] by demonstrating that the determination of a people to fight for their sovereignty and right to self-determination was an unconquerable force, even in the face of Pentagon might."

Synonyms

All synonyms
5-gonfigurefinpentagramphoebequinquangle

Example

More examples

"Pentagon officials won't say when the problem turned up and refused to discuss details about the flight."

Etymology

Etymology 1

From Middle French pentagone, from Late Latin pentagōnum, from Ancient Greek πεντάγωνον (pentágōnon), noun use of the neuter of the adjective πεντάγωνος (pentágōnos, “five-angled”), from πέντε (pénte, “five”) + -γωνος (-gōnos, “angled”). Equivalent to penta- + -gon.

Etymology 2

From the shape of the building.

Related phrases

they hit the Pentagon

More for "pentagon"

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.