Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Either of two points on the celestial sphere at which the ecliptic intersects the celestial equator.
  • n. Either of the two times during a year when the sun crosses the celestial equator and when the length of day and night are approximately equal; the vernal equinox or the autumnal equinox.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The intersection of the ecliptic (apparent path of the sun) with the celestial equator.

from the GNU version of the Collaborative International Dictionary of English

  • n. The time when the sun enters one of the equinoctial points, that is, about March 21 and September 22. See Autumnal equinox, Vernal equinox, under autumnal and vernal.
  • n. Equinoctial wind or storm.

from The Century Dictionary and Cyclopedia

  • n. The moment when the sun crosses the plane of the earth's equator, making the day and night everywhere of equal length (whence the name). There are two annual equinoxes, the vernal, which falls in the spring, namely, on the 21st of March according to the Gregorian calendar, and the autumnal, which falls in the autumn, namely, on the 22d of September. The term equinox is also loosely applied to the equinoctial points (which see, under equinoctial).
  • n. An equinoctial gale or storm; an equinoctial.
  • n. Anything equal; an equal measure.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. (astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic
  • n. either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length

Etymologies

Middle English, from Old French equinoxe, from Medieval Latin aequinoxium, from Latin aequinoctium : aequi-, equi- + nox, noct-, night.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin aequinoctium, from aequus ("equal") + nox ("night"). (Wiktionary)

Examples

  • The word equinox comes from the Latin words for "equal" and "night."

    CBC | Top Stories News

  • Instead of Summer and Winter Solstice, it should be Periuma and Apuma, and without an axial tilt the term equinox is moot -- every day is equal amounts of day and night.

    Coyote Rising by Allen Steele

  • The Truth: The vernal equinox is one of two days each year when the length of day and night are the same (about 12 hours each).

    Busted Science Myths

  • Spring equinox is upon us again, so it's time for the annual "Cumbre Tajín" festival, which will run from the 19th thru the 23rd of March.

    Cumbre Taj�n

  • Placing Easter near the vernal equinox is good symbolism.

    Let go of the past

  • The day of the spring equinox is supposed to be the best day to climb to the top of any pyramid to renew your energy.

    Has Ajijic lost its "charm?"

  • The somnolent gloom thrown by the massed foliage gives majesty to the summer field; and how splendid, on some loud day in the equinox, is the sight of the dumb shadows of the shouting, gesticulating trees, tossing and bending, lengthening and shrinking over the land.

    The Spring of Joy: A Little Book of Healing

  • The word equinox implies the condition that the night is equal to the day.

    Great Astronomers

  • The official church date for the equinox is March 21, but as the Eastern Orthodox use the Julian calendar while Western churches use the Gregorian, both of which designate March 21 as the equinox, the actual date of Easter ranges from March 22 to April 15.

    Daniel Bruno Sanz: Bad Moon, Burnt Qurans, Birthers and Flat Earthers

  • These colors are connected to the fall equinox, which is around the 20th or 21st of September each year and is sometimes called “Mabon.”

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Comments

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  • I first met the equinoxes in The Elephant's Child:

    That very next morning, when there was nothing left of the Equinoxes, because the Precession had preceded according to precedent, this 'satiable Elephant's Child took a hundred pounds of bananas (the little short red kind), and a hundred pounds of sugar-cane (the long purple kind), and seventeen melons (the greeny-crackly kind), and said to all his dear families, 'Goodbye. I am going to the great grey-green, greasy Limpopo River, all set about with fever-trees, to find out what the Crocodile has for dinner.'

    Kipling, Just So Stories

    March 27, 2007