| Equinox 1. (n.) The time when the sun enters one of the equinoctial points, that is, about March 21 and September 22. See Vernal. 2. (n.) Equinoctial wind or storm. Thesaurus Entries aphelion, apogee, astronomical longitude, autumnal equinox, celestial equator, celestial longitude, celestial meridian, circle, colures, ecliptic, equator, equinoctial, equinoctial circle, equinoctial colure, galactic longitude, geocentric longitude, geodetic longitude, great circle, heliocentric longitude, longitude, meridian, orbit, perigee, perihelion, period, small circle, solstice, solstitial colure, summer solstice, trajectory, vernal equinox, winter solstice, zodiac, zone |