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e·qui·nox

(ekwə-nŏks′, ĕkwə-)

1. Either of two points on the celestial sphere at which the ecliptic intersects the celestial equator.

2. 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.

[Middle English, fromOld Frenchequinoxe, fromMedieval Latinaequinoxium, fromLatinaequinoctium : aequi-, equi- + nox, noct-, night; see nek^w-t- in the Appendix of Indo-European roots.]

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equinox

celestial sphere showing the positions of the autumnal and vernal equinoxes

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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