equinox

noun

1
: either of the two points on the celestial sphere where the celestial equator intersects the ecliptic
2
: either of the two times each year (as about March 21 and September 23) when the sun crosses the equator and day and night are everywhere on earth of approximately equal length

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Equinox and the Seasons

Equinox descends from aequus, the Latin word for "equal" or "even," and nox, the Latin word for "night"—a fitting history for a word that describes days of the year when the daytime and nighttime are equal in length. In the northern hemisphere, the vernal equinox marks the first day of spring and occurs when the sun moves north across the equator. (Vernal comes from the Latin word ver, meaning "spring.") The autumnal equinox marks the first day of autumn in the northern hemisphere and occurs when the sun crosses the equator going south. In contrast, a solstice is either of the two moments in the year when the sun's apparent path is farthest north or south from the equator.

Examples of equinox in a Sentence

Recent Examples on the Web That makes the weeks around September 22’s fall equinox worth penciling in either for a trip to the Arctic Circle (to Alaska or far northern Europe) or to have a dark sky site in mind to drive to if another rare show of global aurora is predicted. Jamie Carter, Forbes, 23 Sep. 2024 Driving the news: The fall equinox was yesterday, marking the first day of the fall season. Alex Fitzpatrick, Axios, 23 Sep. 2024 There is also a spring equinox which signifies a similar transition, in contrast to the summer and winter solstices that occur. Skyler Caruso, Peoplemag, 21 Sep. 2024 Here’s how to make the most of the equinox’s powerful energy this year. Vivianne Crowley, Vogue, 21 Sep. 2024 See all Example Sentences for equinox 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'equinox.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Middle English, from Anglo-French or Medieval Latin; Anglo-French equinocce, from Medieval Latin equinoxium, alteration of Latin aequinoctium, from aequi- equi- + noct-, nox night — more at night

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of equinox was in the 14th century

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Cite this Entry

“Equinox.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/equinox. Accessed 10 Oct. 2024.

Kids Definition

equinox

noun
: either of the two times each year about March 21 and September 23 when the sun appears overhead at the equator and day and night are everywhere of equal length
Etymology

Latin equinoxium (same meaning), derived from earlier Latin aequi- "equal" and noct-, nox "night" — related to nocturnal

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