noun

equinox

EHK-wih-noks

noun

Either of the two times a year (around March 20 and September 22) when day and night are of roughly equal length everywhere on Earth.

"The spring equinox marks the start of longer, warmer days in the north."

"Many ancient cultures held festivals around the autumn equinox."

How to Use Equinox

Learner’s notes

In plain EnglishThe day, twice a year, when day and night last about the same amount of time.

Common mistake

Don't confuse with a solstice — the equinox is when day and night are equal; the solstice is when one of them is at its longest or shortest.

Easily confused with

solstice →

Common pairings

spring equinox autumn equinox vernal equinox

equinoxes plural, equinoctes plural

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The spring _____ marks the start of longer, warmer days in the north.

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