equinox

noun
equi·​nox | \ ˈē-kwə-ˌnäks How to pronounce equinox (audio) , ˈe- How to pronounce equinox (audio) \

Definition of equinox

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," 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

There are two solstices — one in the summer, one in the winter — and two equinoxes — one in the spring, one in the fall — every year. Andrew Clark, Indianapolis Star, "What is the summer solstice? A brief explainer," 19 June 2019 And popular demand has inspired new programming, including the Astronomy Fest, a 2016 addition that occurs during the autumnal equinox. National Geographic, "Find epic stargazing at ‘New Mexico’s Machu Picchu’," 25 Mar. 2019 Similarly, casting your incantation at the intersection of day and night (dawn or dusk), as well as during seasonal equinoxes, can strengthen its potency. Aliza Kelly Faragher, Allure, "A Beginner's Guide to Casting Your Own Spells at Home," 26 Mar. 2018 During an equinox the length of day and night of the Northern and Southern Hemispheres are nearly the same. Time, "This Is What the Spring Equinox Looks Like From Space," 20 Mar. 2018 Spring is officially here, and the spring equinox is a welcome reminder that warmer days are, in fact, ahead. Jenna Rennert, Vogue, "The Definitive Guide to Surviving Allergy Season," 22 Mar. 2019 In his paper, Dash suggests that ancient Egyptians did in fact use the sun to align the pyramids—but specifically on the day of the fall equinox. Brigit Katz, Smithsonian, "Is the Fall Equinox the Secret to the Pyramids’ Near-Perfect Alignment?," 22 Feb. 2018 But one strong possibility is that it was used to mark solstices and equinoxes. Brian Resnick, Vox, "The winter solstice is Friday: 8 things to know about the shortest day of the year," 18 Dec. 2018 Endurance training: Equinox over the decades September 23, 1991 The first Equinox opens, on the autumnal equinox, on Manhattan’s Upper West Side. Howie Kahn, WSJ, "The Hotel Where You’ll Be ‘Sleep-Coached’ Into Bed," 27 Mar. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'equinox.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of equinox

14th century, in the meaning defined at sense 1

History and Etymology for equinox

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

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Last Updated

25 Jun 2019

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Time Traveler for equinox

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

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More Definitions for equinox

equinox

noun

English Language Learners Definition of equinox

: a day when day and night are the same length

equinox

noun
equi·​nox | \ ˈē-kwə-ˌnäks How to pronounce equinox (audio) , ˈe-kwə-\

Kids Definition of equinox

: either of the two times each year (as in spring around March 21 and in fall around September 23) when the sun's center crosses the equator and day and night are everywhere of equal length

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More from Merriam-Webster on equinox

Rhyming Dictionary: Words that rhyme with equinox

Spanish Central: Translation of equinox

Nglish: Translation of equinox for Spanish Speakers

Britannica English: Translation of equinox for Arabic Speakers

Britannica.com: Encyclopedia article about equinox

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