equinox.

One of the two times each year when the sun crosses the celestial equator and day and night are approximately equal in length.

Use it for

Words that belong together

• spring equinox
• autumn equinox

On the page

The colony marked the equinox with its first outdoor gathering.

Usage notes

Primary category: sci-fi. Forms: Singular equinox; plural equinoxes. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings. Established modern English lexical item. No separate regional spelling or grammatical inflection entry. Commonness: moderately common.