'Equinoctial' definitions:

Definition of 'equinoctial'

adjective

Relating to the vicinity of the equator

adjective

Relating to an equinox (when the lengths of night and day are equal)

noun

The great circle on the celestial sphere midway between the celestial poles [syn: celestial equator, equinoctial circle, equinoctial line, equinoctial]

From: GCIDE

From: GCIDE

Equinoctial \E`qui*noc"tial\, a. [L. aequinoctials, fr. aequinoctium equinox: cf. F. ['e]quinoxial. See Equinox.]
1. Pertaining to an equinox, or the equinoxes, or to the time of equal day and night; as, the equinoctial line. [1913 Webster]
2. Pertaining to the regions or climate of the equinoctial line or equator; in or near that line; as, equinoctial heat; an equinoctial sun. [1913 Webster]
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. [1913 Webster]
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. [1913 Webster]
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. [1913 Webster]

From: GCIDE

Equator \E*qua"tor\, n. [L. aequator one who equalizes: cf. F. ['e]quateur equator. See Equate.]
1. (Geog.) The imaginary great circle on the earth's surface, everywhere equally distant from the two poles, and dividing the earth's surface into two hemispheres. [1913 Webster]
2. (Astron.) The great circle of the celestial sphere, coincident with the plane of the earth's equator; -- so called because when the sun is in it, the days and nights are of equal length; hence called also the equinoctial, and on maps, globes, etc., the equinoctial line. [1913 Webster]
Equator of the sun or Equator of a planet (Astron.), the great circle whose plane passes through through the center of the body, and is perpendicular to its axis of revolution.
Magnetic equator. See Aclinic. [1913 Webster]