Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Either of two points on the celestial sphere at which the ecliptic intersects the celestial equator.
  • noun 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 The Century Dictionary.

  • noun 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).
  • noun An equinoctial gale or storm; an equinoctial.
  • noun Anything equal; an equal measure.

from the GNU version of the Collaborative International Dictionary of English.

  • noun 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.
  • noun rare Equinoctial wind or storm.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

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

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

  • noun (astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic
  • noun 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

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

[Middle English, from Old French equinoxe, from Medieval Latin aequinoxium, from Latin aequinoctium : aequi-, equi- + nox, noct-, night; see nekw-t- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin aequinoctium, from aequus ("equal") + nox ("night").

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

  • 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

  • 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

  • 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

  • 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

  • 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?"

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