octagon

Etymology

It is partly borrowed from Latin octagōnon, also octōgōnon, and partly borrowed from Ancient Greek ὀκτάγωνον (oktágōnon),^[2][3][4] the noun use of the neuter of ὀκτάγωνος (oktágōnos, “eight-cornered”), which is attested later, in Hellenistic Greek.^[2][3][5] Barnhart and Etymonline give the Latin form as octagōnos.^[6][7] The Greek adjective is formed from ὀκτα- (okta-), the combining form of ὀκτώ (oktṓ, “eight”), and the stem of γωνία (gōnía, “corner, angle”),^[2][7][5] which is related to γόνυ (gónu, “knee”),^[7][6][4] from Proto-Indo-European *genu- (“knee; angle”), the source of knee.^[7][4] Barnhart and Etymonline also record a form octogon (1656, in Blount's “Glossographia”) from French octogone,^[8][7] and the OED compares Middle French octogone (a noun from 1484, an adjective from 1547), Italian ottagono and Spanish octágono.^[2] The adjective octagonal is recorded earlier than the noun, from 1571.^[2][7]

Earliest recorded meaning

A plane figure with eight straight sides and eight angles, also a building or object of that shape: 1594, in the Warrender Papers.^[2][4] Barnhart dates the word to 1660,^[6] and Etymonline to the 1650s.^[7]

Semantic evolution

Johnson (1755), following Harris, added that an octagon with equal sides and angles is called regular and can be inscribed in a circle.^[9] From 1648 to 1728 it also named a fort with eight bastions,^[2] and it was used as an adjective meaning octagonal from 1679.^[2][10] In the late 18th century the Octagon was the name of an octagonal building in Liverpool used for worship by a dissenting sect (1767).^[2] Collins records Octagon as a trademark for the eight-sided fenced mat on which mixed martial arts bouts are fought.^[11]

Timeline

• 1594 – a plane figure with eight sides and angles; a building or object of that shape.^[2][4]
• 1648 – in fortification, a fort with eight bastions (obsolete after 1728).^[2]
• 1679 – adjective, octagonal.^[2]
• 1767 – an octagonal chapel in Liverpool used by a dissenting sect.^[2]

Meanings

Noun

1. A polygon with eight sides and eight angles.^{[3][4][11][2]}
2. An object or building of octagonal shape: The chapter house is an octagon with a vaulted roof.^[4][2]
3. Octagon (trademark): the eight-sided, fenced mat used for mixed martial arts contests.^[11]

Adjective

1. Having eight sides; octagonal.^[2][10]

Word family

• octagonal
• octagonally

Related words

• eight
• knee
• polygon
• diagonal
• pentagon
• hexagon

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
4. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
7. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
9. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
10. ^ a b The Chambers Dictionary (2008), 11th ed., Edinburgh: Chambers Harrap
11. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins