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
Did You Know?
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.
"The first recorded New Year’s celebration traces back to Mesopotamia, where 4,000 years ago the ancient Babylonians kicked off an 11-day festival called Akitu on the vernal equinox." — Cody Cottier, Discover (discovermagazine.com), 30 Dec. 2020
"Groundhog Day's origins lie in the ancient European celebration of Candlemas, which is a point midway between the winter solstice and the spring equinox—the exact midpoint of astronomical winter." — Doyle Rice, USA Today, 2 Feb. 2021
Test Your Vocabulary with M-W Quizzes
Word Family Quiz
Fill in the blanks to complete a descendant of aequus that refers to an evenness of mind under stress: eq _ _ _ _ m _ _ y.VIEW THE ANSWER
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