n. 1. A polygon with five sides and five angles. 2. Pentagon A five-sided building near Washington DC, containing the US Department of Defense and the offices of the US Armed Forces. Used with the. [Late Latin pentagōnium, from Greek pentagōnon, from neuter of pentagōnos, pentagonal : penta-, penta- + -gōnos, angled; see -GON.] pen·tago·nal (pĕn-tăgə-nəl) adj. pen·tago·nal·ly adv. ![]() (click for a larger image) pentagon![]() (click for a larger image) pentagontop: mathematical figure bottom: the Pentagon Washington, DC |
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