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Syllabification: e·qui·nox
Pronunciation: /ˈekwəˌnäks
, ˈēkwəˌnäks

Definition of equinox in English:


1The time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20).
Example sentences
  • These nine nights occur on equinoxes or equal nights when the sun is vertically overhead at the equator or centre.
  • The lengths of the hours were equal around the equinoxes but the rest of the time they could vary considerably.
  • ‘An equinox is when night and day are equal,’ he said.
1.1 another term for equinoctial point.
Example sentences
  • A tropical year is the time it takes the sun to pass from one equinox, or tropic, to the same tropic or equinox again.
  • The position of the stars should not be related to the point of the equinox, that is to the position of the point which changes position in the course of time, but the position of the point of the equinox should be related to the sphere of stars.


late Middle English: from Old French equinoxe or Latin aequinoctium, from aequi- 'equal' + nox, noct- 'night'.

Definition of equinox in:

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