octagonとは 意味・読み方・使い方

別の表記

• octogon (廃れた用法)

語源

From Latin octagōnon, octōgōnon (“octagon”), and from its etymon Ancient Greek ὀκτάγωνον (oktágōnon, “octagon”), probably from Koine Greek ὀκτάγωνος (oktágōnos, “having eight corners”) + -ον (-on, suffix forming nouns). ὀκτάγωνος is derived from ὀκτᾰ- (okta-, prefix meaning ‘eight’) (from ὀκτώ (oktṓ, “eight”), ultimately from Proto-Indo-European *oḱtṓw (“eight”)) + γωνία (gōnía, “angle; corner”) (probably ultimately from Proto-Indo-European *ǵónu (“knee”));^[1] analysable as octa- +‎ -gon. The English word is cognate with Middle French octogone (modern French octogone), Italian octagono (廃れた用法), ottagono, Spanish octágono, octógono.^[1]

Sense 2 (“arena for mixed martial arts”) refers to its shape.

発音

• (Received 発音) enPR: ŏk'təgən, IPA^(key): /ˈɒktəɡ(ə)n/
• (General American) enPR: ŏk'təgŏn, IPA^(key): /ˈɑktəˌɡɑn/
• ハイフネーション: oc‧ta‧gon

名詞

octagon (複数形 octagons)

1. (geometry, also attributively) A polygon with eight sides and eight angles.
   • 1707, Andrea Pozzo, “The Ninety-second Fig. An Octangular Cupola.”, in John James, transl., Rules and Examples of Perspective Proper for Painters and Architects, etc. in English and Latin: […], London: […] Benj[amin] Motte [Sr.], […]; [s]old by John Sturt […], →OCLC:

     From the Circle deſcribe the Octagon, by taking half the Quadrant of the former for each Side of the latter. [...] [B]y conjoining theſe Points with ſtrait Lines agreeable to the Shape of the Octagon, the whole Work is completed.

   • 1752, Euclid, “[Additions to the Fourth Book.] Prop[osition] VII. Probl[em]. To Describe any Regular Polygon upon a Given Right Line, Admitting the Division of a Given Arch of a Circle into any Number of Equal Parts.”, in E[dmund] Stone, transl., Euclid’s Elements of Geometry, the First Six, the Eleventh and Twelfth Books; […], London: […] Tho[mas] Payne, […], →OCLC, book IV, pages 199–200:

     In like manner it is demonſtrated that one angle of a regular hexagon will be equal to one right angle, and one third part of one right angle; one angle of a regular octagon equal to one right angle and half a right angle; [...]

   • 1808, William Nicholson, “Ores of Bismuth”, in A Dictionary of Practical and Theoretical Chemistry, […], London: […] Richard Phillips, […], →OCLC, column 2:

     Bismuth is the most common of all native metallic substances. It is generally found either in cubes or octagons, or of a dendritical form, or else in thin laminæ investing the ores of other metals, particularly those of cobalt.

   • 1810, [James Sargant Storer; John Grieg], “Worlingworth Church, Suffolk”, in Antiquarian and Topographical Cabinet, Containing a Series of Elegant Views of the Most Interesting Objects of Curiosity in Great Britain. […], volume VII, London: […] W. Clarke, […], →OCLC:

     The font is an octagon, having at each angle a slender pillar with crockets and finials, and the sides are richly sculptured with angels and animals, the figures holding shields, with various devices; at each corner of the contracting part towards the pedestal, are cherubs heads with expanded wings; and the pedestal, which is an irregular octagon, is ornamented with four non-descript animals, scaled over their breasts; on a moulding round the bottom are several old characters, now illegible.

   • 1863 June 1, [Charles William] Selwyn, “Supply—Civil Service Estimates. Supply Considered in Committee.”, in Hansard’s Parliamentary Debates, […] (House of Commons), volume CLXXI, London: Published by Cornelius Buck, at the office for “Hansard’s Parliamentary Debates,” […], →OCLC, columns 214–215:

     The building [the Winter Garden conservatory, Kew Gardens] was to be of five parts—a centre, two small octagons, and two wings connected by the octagons with the centre. The centre and the two octagons were finished, and some expenditure must have been laid out on the wings, as the ground was dug out and foundations in concrete laid for the pillars.

   • 1922 October 28, Roy C. Bennett, “Rug Gift to National Press Club Typifies New China Industry”, in J[ohn] B[enjamin] Powell, editor, The Weekly Review, volume XXII, number 9, Shanghai: Millard Publishing Company, →OCLC, page 299, column 2:

     China converted the hard octagons of the Turkoman rugs into circular scrolls or medallions, beautifying them meanwhile with floral character manifestly borrowed from the Persians and yet by no means Persian.

2. (martial arts) Often in the form Octagon: the arena for mixed martial arts.

派生語

• octagonal
• octagonally

参照

Further reading

• octagon on Wikipedia.
• The Octagon, Dunedin on Wikipedia.