equinox

noun

equi·nox ˈē-kwə-ˌnäks

ˈe-

: either of the two points on the celestial sphere where the celestial equator intersects the ecliptic

: 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

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

However, the geomagnetic storms that produce them tend to be more frequent and intense around the equinoxes. —

Jamie Carter, Forbes, 31 Dec. 2024 Winter lasts until the spring equinox on March 20, 2025. —

Tiffany Acosta, The Arizona Republic, 2 Dec. 2024 Winter will end when the vernal equinox begins – in 2025, that’s Thursday, March20. —

Clare Mulroy, USA TODAY, 8 Nov. 2024 That's because the closest full moon to the autumnal equinox is called the Harvest Moon, which often happens in September. —

John Tufts, The Indianapolis Star, 16 Oct. 2024 See all Example Sentences for equinox

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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Style

“Equinox.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/equinox. Accessed 14 Jan. 2025.

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Kids Definition

equinox

noun

equi·nox ˈē-kwə-ˌnäks

ˈek-wə-

: 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

Last Updated: 14 Jan 2025 - Updated example sentences

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equinox

noun

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Examples of equinox in a Sentence

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