adj. & n.
adj. 1 happening at or near the time of an equinox (equinoctial gales). 2 of or relating to equal day and night. 3 at or near the (terrestrial) equator.
n. (in full equinoctial line) = celestial equator. equinoctial point the point at which the ecliptic cuts the celestial equator (twice each year at an equinox). equinoctial year see YEAR.
[ ME f. OF equinoctial or L aequinoctialis (as EQUINOX) ]