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.
Phrases and idioms:
equinoctial point the point at which the ecliptic cuts the celestial equator (twice each year at an equinox). equinoctial year see YEAR.
Etymology: ME f. OF equinoctial or L aequinoctialis (as EQUINOX)