from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A polygon having five sides and five interior angles.
  • n. A five-sided building near Washington, D.C., containing the U.S. Department of Defense and the offices of the U.S. Armed Forces. Used with the.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A polygon with five sides and five angles.

from the GNU version of the Collaborative International Dictionary of English

  • n. A plane figure having five angles, and, consequently, five sides; any figure having five angles.

from The Century Dictionary and Cyclopedia

  • n. In geometry, a figure of five sides and five angles: if all the sides and all the angles are equal it is a regular pentagon.
  • n. In fortification, a fort with five bastions.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the United States military establishment
  • n. a five-sided polygon
  • n. a government building with five sides that serves as the headquarters of the United States Department of Defense


Late Latin pentagōnum, from Greek pentagōnon : penta-, penta- + -gōnon, -gon.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From French pentagone or late Latin pentagonum, from Ancient Greek πεντάγωνον, noun use of the neuter of the adjective πεντάγωνος ("five-angled"), from πέντε ("five") + -γωνος ("angled"). (Wiktionary)



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  • Also a surprisingly good (and old) cover band from central PA. I remember them saying on stage once, "Man, other bands get named after cattle diseases, and all we got was a building."

    August 2, 2008

  • The U.S. Department of Defense.

    January 10, 2008