We found 37 dictionaries that define the word pentagon:

General (26 matching dictionaries)

1. pentagon: Longman Dictionary of Contemporary English
2. Pentagon, pentagon, the Pentagon, the pentagon: Merriam-Webster
3. pentagon, the Pentagon: Oxford Learner's Dictionaries
4. pentagon: American Heritage Dictionary of the English Language
5. pentagon: Collins English Dictionary
6. Pentagon, pentagon: Vocabulary.com
7. Pentagon, pentagon: Wordnik
8. pentagon, the Pentagon, the pentagon: Cambridge Advanced Learner's Dictionary
9. Pentagon, pentagon: Wiktionary
10. pentagon: Webster's New World College Dictionary, 4th Ed.
11. pentagon: The Wordsmyth English Dictionary-Thesaurus
12. pentagon: Infoplease Dictionary
13. Pentagon, the pentagon: Dictionary.com
14. pentagon: Online Etymology Dictionary
15. pentagon: Cambridge Essential American English Dictionary
16. Pentagon (Brussels), Pentagon (EP), Pentagon (Japanese band), Pentagon (South Korean band), Pentagon (TV series), Pentagon (USA), Pentagon (United States), Pentagon (Washington Metro), Pentagon (Wiesbaden), Pentagon (band), Pentagon (building), Pentagon (computer), Pentagon (disambiguation), Pentagon (military), Pentagon (novel), Pentagon (shape), Pentagon, The Pentagon (album), The Pentagon, The pentagon: Wikipedia, the Free Encyclopedia
17. Pentagon: Online Plain Text English Dictionary
18. pentagon: Webster's Revised Unabridged, 1913 Edition
19. Pentagon: Rhymezone
20. Pentagon: AllWords.com Multi-Lingual Dictionary
21. pentagon: Webster's 1828 Dictionary
22. pentagon: FreeDictionary.org
23. pentagon: Mnemonic Dictionary
24. pentagon: TheFreeDictionary.com

Art (1 matching dictionary)

25. pentagon: ArtLex Lexicon of Visual Art Terminology

Business (1 matching dictionary)

26. Construction Term Glossary (No longer online)

Computing (1 matching dictionary)

27. Pentagon (shape), pentagon: Encyclopedia

Medicine (1 matching dictionary)

28. online medical dictionary (No longer online)

Miscellaneous (3 matching dictionaries)

29. Encyclopedia of Graphic Symbols (No longer online)
30. Glossary of Terrorism Terms (No longer online)
31. Third Eye's Paranormal (No longer online)

Science (2 matching dictionaries)

32. Pentagon: Eric Weisstein's World of Mathematics
33. pentagon: PlanetMath Encyclopedia

Slang (2 matching dictionaries)

34. Totally Unofficial Rap (No longer online)
35. Pentagon: Urban Dictionary

(Note: See pentagons as well.)

Definitions from Wiktionary ( ) ▸ noun:  (geometry) A polygon with five sides and five angles. ▸ noun:  (military) A fort with five bastions. ▸ noun:  The headquarters of the United States Department of Defense. ▸ noun:  (metonymically) The United States Department of Defense. Similar: pentagonohedron, hexagon, heptagon, quadrangle, pentahedron, octagon, pentangle, 5-cell, quadrilateral, dihectagon, more... Opposite: hexagon Types: regular, convex, concave, self-intersecting, star, more... Phrases: The Pentagon, Pentagon Papers, regular pentagon, pentagon gang, Pentagon UFO videos, more... Adjectives: regular, irregular, inscribed, equilateral, racial, required, radial, perfect, central, simple, smaller Colors:     olive,     khaki,     coyote brown,     desert sand,     sage green, more... ▸ Word origin ▸ Words similar to pentagon ▸ Usage examples for pentagon ▸ Idioms related to pentagon ▸ Wikipedia articles (New!) ▸ Popular adjectives describing pentagon ▸ Words that often appear near pentagon ▸ Rhymes of pentagon ▸ Invented words related to pentagon