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.

During the March equinox, the Northern Hemisphere and Southern Hemisphere receive roughly the same amount of sunlight since neither hemisphere is tilted more toward or away from the sun, the almanac said. —

Hannah Poukish, Sacramento Bee, 12 Feb. 2025 This drift carries the node early this year through the March equinox, and hence the moon's path is tilted 23.5 degrees + 5 degrees = 28.5 degrees to the equator. —

Joe Rao, Space.com, 7 Feb. 2025 Taking place the day before the southward equinox, the most dramatic views will be in New Zealand, where up to 73% of the sun will be obscured at sunrise. —

Jamie Carter, Forbes, 1 Jan. 2025 In the Northern Hemisphere, the autumnal equinox is Sept. 22, marking the start of the fall season. —

Haadiza Ogwude, The Enquirer, 28 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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“Equinox.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/equinox. Accessed 19 Feb. 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: 19 Feb 2025 - Updated example sentences

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equinox

noun

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Examples of equinox in a Sentence

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