E·qui·noc·tial a.
 1. Pertaining to an equinox, or the equinoxes, or to the time of equal day and night; as, the equinoctial line.
 2. Pertaining to the regions or climate of the equinoctial line or equator; in or near that line; as, equinoctial heat; an equinoctial sun.
 3. Pertaining to the time when the sun enters the equinoctial points; as, an equinoctial gale or storm, that is, one happening at or near the time of the equinox, in any part of the world.
 Equinoctial colure Astron., the meridian passing through the equinoctial points.
 Equinoctial line Astron., the celestial equator; -- so called because when the sun is on it, the nights and days are of equal length in all parts of the world. See Equator.
 Thrice the equinoctial line
 He circled.   --Milton.
 -- Equinoctial points Astron., the two points where the celestial and ecliptic intersect each other; the one being in the first point of Aries, the other in the first point of Libra.
 Equinoctial time Astron. reckoned in any year from the instant when the mean sun is at the mean vernal equinoctial point.