equinoxとは意味・読み方・使い方

出典:『Wiktionary』 (2025/11/04 13:12 UTC 版)

WOTD – 23 September 2022

語源

During an equinox (sense 1) at noon according to Central European Time (ignoring daylight saving time), the Sun’s rays illuminate the Earth as shown in this diagram.

A diagram showing where the equinoxes (sense 3) occur in space relative to the Earth and the Sun. As the Sun appears to move around the Earth (actually, it is the Earth that moves around the Sun), its apparent path (the ecliptic; yellow circle) first intersects with the Earth’s equatorial plane (blue disc) in March at the green dot marked “first point of Aries”, and then again in September at the green dot marked “first point of Libra”. In the Northern Hemisphere, the March equinox is called the spring equinox as it traditionally marks the start of spring, while the September equinox is the autumn equinox that marks the start of autumn. It is the other way around in the Southern Hemisphere.

From 中期英語 equinox, equinoxe, equynox (“one of the two periods in the year when the day and night are of equal length, equinox; either the zodiac sign Aries or Libra, in which the sun crosses the celestial equator”), from Old French equinoce, equinoxe (modern French équinoxe), or from its etymon Medieval Latin ēquinoxium, ēquinoctium, from Latin aequinoctium (“equinox”), from aequus (“equal”) + nox (“night”) (ultimately derived from Proto-Indo-European *nókʷ ts (“night”)) + -ium (suffix forming abstract nouns). The Latin word, ultimately adopted in 中期英語 and modern English, displaced 古期英語 efnniht (modern English evennight).

The rare alternative plural form equinoctes treats equinox as if it were a Latin word; the plural of Latin nox (“night”) is noctēs.

発音

Singular:
- (Received Pronunciation) IPA: /ˈɛkwɪnɒks/, /ˈiː-/
- (General American) IPA: /ˈɛkwəˌnɑks/, /ˈi-/
- (Canada) IPA: /ˈɛkwɪˌnɑks/, /ˈiː-/
- ハイフネーション: equi‧nox
Plural (equinoctes):
- (Received Pronunciation) IPA: /ˌɛkwɪˈnɒktiːz/, /ˌiː-/
- (General American) IPA: /ˌɛkwəˈnɑktiz/, /ˌi-/
- (Canada) IPA: /ˌɛkwɪˈnɑktiz/, /ˌi-/
- ハイフネーション: equi‧noc‧tes

名詞

equinox (plural equinoxes or (rare) equinoctes)

One of two times in the year (one in March and the other in September) when the length of the day and the night are equal, which occurs when the sun is directly overhead at the equator; this marks the beginning of spring in one hemisphere and autumn in the other.

Synonym: (rare) evennight
- 1692 December 15, Richard Bentley, A Confutation of Atheism from the Origin and Frame of the World. The Third and Last Part. […], London: […] H[enry] Mortlock […], published 1693, →OCLC, pages 25–26:
  
  [T]he Months of March and September, the tvvo Æquinoxes of Our year, are the moſt vvindy and tempeſtuous, the moſt unſettled and unequable of Seaſons in moſt Countries of the VVorld.
- 1793 September 22, Edward Williams, “Ode on Converting a Sword into a Pruning Hook”, in Poems, Lyric and Pastoral. […], London: […] J[ohn] Nichols; […], published 1794, →OCLC, footnote *, pages 160–161:
  
  The four grand and ſolemn Bardic days are, of ancient uſage, the tvvo equinoxes, and the tvvo ſolſtices; the nevv and full moons are al ſo, ſubordinately, ſolemn Bardic days: […]
- 1838 July, Ralph Waldo Emerson, “Milton”, in J[ames] E[lliot] Cabot, editor, The Natural History of the Intellect (Emerson’s Complete Works; XII), Riverside edition, London: The Waverley Book Company, published 1893, →OCLC, page 155:
  
  [H]e [Milton] believed, his poetic vein only flowed from the autumnal to the vernal equinox; and, in his essay on Education, he doubts whether, in the fine days of spring, any study can be accomplished by young men.
- 1842, Alfred Tennyson, “Will Waterproof’s Lyrical Monologue”, in Poems. […], volume II, London: Edward Moxon, […], →OCLC, page 194:
  
  Live long, nor feel in head or chest / Our changeful equinoxes, / Till mellow Death, like some late guest, / Shall call thee from the boxes.
- 1848, Charles Richard Weld, chapter V, in A History of the Royal Society, with Memoirs of the Presidents. […], volume I, London: John W[illiam] Parker, […], →OCLC, page 100:
  
  21. Report the experiments, if conveniently they may, at both the solstices and equinoctes. / 22. Observe accurately the time of the sun’s rising on the top of the hill and below, and note the difference.
- 1854, John Williams, “Pro-consul. b.c. 55.”, in The Life of Julius Cæsar, London; New York, N.Y.: G[eorge] Routledge & Co., […], →OCLC, page 195:
  
  For [Julius] Cæsar says, that on the night of the fourth day after his landing there was a full moon. He had before mentioned that the summer was far spent, and the æquinox not come, hence, the full moon must have been either in July or August.
- 2005, Clive [L. N.] Ruggles, “Equinoxes”, in Ancient Astronomy: An Encyclopedia of Cosmologies and Myth, Santa Barbara, Calif.: ABC-CLIO, →ISBN, page 148:
  
  The word equinox is generally taken to refer to the days when, at every point on the earth, day and night are of equal length. But this definition of the equinox is a bit misleading. Since it gets light before the sun rises and remains light after the sun sets, the actual period of darkness at the equinox will be substantially less than twelve hours, the exact amount depending on latitude and how one defines the boundary between twilight and night. […] In practice, one cannot determine the equinox by measuring the length of time between sunrise and sunset.
- 2006, John T. Koch, “calendar, Celtic”, in Celtic Culture: A Historical Encyclopedia, volume I, Santa Barbara, Calif.: ABC-CLIO, →ISBN, §4 (The Seasons), page 332, column 1:
  
  […] Midsummer’s Day falls near the beginning of summer meteorologically, but was the midpoint of summer in the traditional calendar. Though Midsummer’s Day celebrations are common in the modern Celtic countries, there is no evidence that the ancient Celts celebrated either the solstices or the equinoctes.
(also figuratively) The circumstance of a twenty-four hour time period having the day and night of equal length.
- c. 1603–1604 (date written), William Shakespeare, The Tragœdy of Othello, the Moore of Venice. […] (First Quarto), London: […] N[icholas] O[kes] for Thomas Walkley, […], published 1622, →OCLC, [Act II, scene iii], page 32:
  
  [D]oe but ſ ee his vice, / Tis to his vertue, a iu ſt equinox, / The one as long as th'other: […]
(astronomy) One of the two points in space where the apparent path of the Sun intersects with the equatorial plane of the Earth.
(obsolete)
1. (rare) A gale (“very strong wind”) once thought to occur more frequently around the time of an equinox (sense 1), now known to be a misconception; an equinoctial gale.
  - 1687, [John Dryden], “The Third Part”, in The Hind and the Panther. A Poem, in Three Parts, 2nd edition, London: […] Jacob Tonson […], →OCLC, page 101:
    
    The paſſage yet vvas good, the vvind, 'tis true, / VVas ſomevvhat high, but that vvas nothing nevv, / Nor more than uſual Equinoxes blevv.
  - 1920 September 1, Rudyard Kipling, “The Satisfaction of a Gentleman”, in The London Magazine, London: Hunt and Clarke, […], →OCLC; republished on the website of The Kipling Society‎, accessed 7 September 2022, archived from the original on 22 December 2021:
    
    The Equinox drove the sand into their faces or round their legs, as they dived among the sheep-haunted hollows.
2. (astronomy) A celestial equator (“great circle on the celestial sphere, coincident with the plane of the Earth 's equator (the equatorial plane)”); also, the Earth's equator.
  
  Synonym: (obsolete) equinoctial line
  - 1697, William Dampier, chapter IV, in A New Voyage Round the World. […], London: […] James Knapton, […], →OCLC, page 90:
    
    [T]hey [seals] are over all the American Coaſt of the South Seas, from Terra del Fuego, up to the Equinoctial Line: but to the North of the Equinox again, in the ſe Sea, I never ſavv any, till as far as 21 North Lat[itude].

別の表記

æquinox (obsolete)

下位語

等位語

solstice

派生語

参考

equilux

参照

^ “ē̆quinox, n.”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007.
^ Compare “equinox, n.”, in OED Online ⁠, Oxford: Oxford University Press, March 2022.
^ “equinox, n.”, in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present, reproduced from Stuart Berg Flexner, editor in chief, Random House Unabridged Dictionary, 2nd edition, New York, N.Y.: Random House, 1993, →ISBN.


	Copyright (c) 1995-2025 Kenkyusha Co., Ltd. All rights reserved.
	Copyright © Benesse Holdings, Inc. All rights reserved.
	© 2000 - 2025 Hyper Dictionary, All rights reserved
	All Rights Reserved, Copyright © Japan Science and Technology Agency
	日本語ワードネット1.1版 (C) 情報通信研究機構, 2009-2010 License All rights reserved. WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved. License
	Copyright © 2025 CJKI. All Rights Reserved
	Copyright (C) 1994- Nichigai Associates, Inc., All rights reserved. 「斎藤和英大辞典」斎藤秀三郎著、日外アソシエーツ辞書編集部編
Wiktionary	Text is available under Creative Commons Attribution-ShareAlike (CC-BY-SA) and/or GNU Free Documentation License (GFDL). Weblio英和・和英辞典に掲載されている「Wiktionary英語版」の記事は、Wiktionaryのequinox (改訂履歴)の記事を複製、再配布したものにあたり、Creative Commons Attribution-ShareAlike (CC-BY-SA)もしくはGNU Free Documentation Licenseというライセンスの下で提供されています。
Wikipedia	Text is available under Creative Commons Attribution-ShareAlike (CC-BY-SA) and/or GNU Free Documentation License (GFDL). Weblio英和・和英辞典に掲載されている「Wikipedia英語版」の記事は、WikipediaのEquinox (改訂履歴)の記事を複製、再配布したものにあたり、Creative Commons Attribution-ShareAlike (CC-BY-SA)もしくはGNU Free Documentation Licenseというライセンスの下で提供されています。
CMUdict	CMUdict is Copyright (C) 1993-2008 by Carnegie Mellon University.

equinoxとは意味・読み方・使い方

equinoxの
品詞ごとの意味や使い方

equinoxの
変形一覧

equinoxの学習レベル

「equinox」を含む例文一覧

研究社新英和中辞典での「equinox」の意味

equinox

Eゲイト英和辞典での「equinox」の意味

equinox

ハイパー英語辞書での「equinox」の意味

equinox

JST科学技術用語日英対訳辞書での「equinox」の意味

equinox

日本語WordNet(英和)での「equinox」の意味

equinox

日英・英日専門用語辞書での「equinox」の意味

equinox

斎藤和英大辞典での「equinox」の意味

equinox

Weblio英和対訳辞書での「equinox」の意味

Equinox

Wiktionary英語版での「equinox」の意味

equinox

語源

発音

名詞

別の表記

下位語

等位語

派生語

関連する語

参考

参照

Further reading

ウィキペディア英語版での「equinox」の意味

Equinox

Weblio例文辞書での「equinox」に類似した例文

equinox

「equinox」を含む例文一覧

「equinox」のお隣キーワード

equinoxとは 意味・読み方・使い方

equinoxの品詞ごとの意味や使い方

equinoxの変形一覧

equinoxの学習レベル

「equinox」を含む例文一覧

equinox

equinox

equinox

equinox

equinox

equinox

equinox

Equinox

equinox

語源

発音

名詞

別の表記

下位語

等位語

派生語

関連する語

参考

参照

Further reading

Equinox

equinox

「equinox」を含む例文一覧

「equinox」のお隣キーワード

equinoxとは意味・読み方・使い方

equinoxの
品詞ごとの意味や使い方

equinoxの
変形一覧