ˈēkwəˌnäks also ˈek- noun
( -es )
Etymology: Middle English, from Middle French or Medieval Latin; Middle French equinoxe, from Medieval Latin equinoxium, alteration of Latin aequinoctium, from aequi- equi- + -noctium (from noct-, nox night) — more at night
1. : either of the two times each year when the sun crosses the equator and day and night are everywhere of equal length, being about March 21 and September 23 — called also respectively vernal equinox, autumnal equinox
2. : either of the two points on the celestial sphere where the celestial equator intersects the ecliptic — compare precession of the equinoxes