- equinox - either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length
--1 is a kind of cosmic time
--1 has particulars:vernal equinox, March equinox, spring equinox; autumnal equinox, September equinox, fall equinox - equinoctial point, equinox - (astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic
--2 is a kind of celestial point
--2 has particulars: vernal equinox; autumnal equinox - equinoctial point, equinox - (astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic