pentagon

Pronunciation

• IPA: /ˈpɛn.təˌɡɑn/, /ˈpɛn.tə.ɡən/^[1]

Etymology

It is borrowed from Middle French pentagone or directly from Late Latin pentagōnum,^{[2][3][4][5][6]} from Ancient Greek πεντάγωνον (pentágōnon), the neuter of pentágōnos “five-angled”,^{[2][3][4][5][6]} from Ancient Greek πέντε (pénte, “five”) + γωνία (gōnía, “angle”).^[3][4][5]

Earliest recorded meaning

A plane figure with five angles and five sides (1560s–71);^[4][3][5][7] as an adjective, five-angled (1570).^[7]

Semantic evolution

In fortification a pentagon was a fort with five bastions (1571).^[7][1] The headquarters of the US Department of Defense in Arlington, Virginia, completed in 1942, was named the Pentagon for its shape,^[4][7][6] and from 1945 the name has been used allusively for the US military leadership.^[4][5]

Timeline

• 1570 – the five-sided figure.^[7][3][5]
• 1571 – a fort with five bastions.^[7]
• 1942 – the Pentagon building completed.^[4]
• 1945 – the US military leadership.^[4][5][7]

Modern meaning

Noun

1. A polygon with five sides and five angles.
2. (the Pentagon) The headquarters of the US Department of Defense; hence, the US military establishment.

Word family

• pentagonal

Related words

• pentagram
• polygon
• hexagon
• octagon
• knee

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
3. ^ a b c d e Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
4. ^ a b c d e f g h Harper, Douglas, Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b c d e f g Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
6. ^ a b c Random House Webster's Unabridged Dictionary (1999), 2nd ed., New York: Random House
7. ^ a b c d e f g Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press