Also 6–7 equinoxe, 6 æquinoxe. 7–8 æquinox. [ad. (directly or through OF. equinoxe) L. æquinoctium (in the Middle Ages spelt equinoxium) equality between day and night, f. æqui- (see EQUI-) + noct- stem of nox night.
The late L. æquinox adj. (f. as æquinoctium) used also as sb. in the sense ‘equinoctial point or sign,’ though not the source of the word as now used, seems to occur in the quot. from Chaucer under 2.]
1. One of the two periods in the year when the days and nights are equal in length all over the earth, owing to the sun’s crossing the equator. Hence, the precise moment at which the sun crosses the equator.
The vernal or spring equinox is at present on the 20 March, and the autumnal on the 22 or 23 September. Just before the reformation of the calendar they were 11 days earlier.
1588. A. King, trans. Canisius’ Catech., H j. To tak away ye ten dayes quhairby ye æquinoxe of springe tyme had passeit ye dew tyme.
1664. Power, Exp. Philos., III. 149. It is eight dayes more from the Vernal to the Autumnal Aequinox, then it is from the Autumnal to the Vernal again.
1692. Bentley, Boyle Lect., 261. The Months of March and September, the two Æquinoxes of Our year, are the most windy and tempestuous.
1726. trans. Gregory’s Astron., I. 246. That he might … bring the Equinox to its former place, ten Days were suppressed in the Month of October, in the Year 1582.
1789. T. Jefferson, Writ. (1859), III. 88. I should put off my departure till after the equinox.
1838. Emerson, Milton, Wks. (Bohn), III. 296. He believed his poetic vein only flowed from the autumnal to the vernal equinox.
1842. Tennyson, Will Waterproof, xxx. Live long, nor feel in head or chest Our changeful equinoxes.
1849. Mrs. Somerville, Connex. Phys. Sc., xiii. 105. At the time of the equinoxes … the sun’s declination is zero.
attrib. 1643. Lightfoot, Glean. Ex., 20. That began exactly from the Equinox day.
b. The condition of having the days and nights of equal length. Also fig.
1604. Shaks., Oth., II. iii. 129. [His vice is] to his vertue, a iust Equinox, The one as long as th’ other.
1696. Whiston, Th. Earth, I. (1722), 58. There must be a perpetual Equinox, or equality of Day and Night, through the whole Planet.
1698. Keill, Exam. Th. Earth (1734), 229. Then the Earth had a perpetual Equinox and unity of Seasons.
2. One of the two points at which the sun’s path crosses the Equator, described technically as the first points in Aries and Libra. Formerly also used loosely for the region of the ecliptic adjacent to these points. Precession of the equinoxes (see PRECESSION).
c. 1391. Chaucer, Astrol., I. § 17. And ther-fore ben thise two signes [Aries & Libra] called the equinoxiis [ed. 1560 equinoctes].
1594. Blundevil, Exerc., 149 a. The beginning of Aries, which is called the vernal Equinoxe.
1635. N. Carpenter, Geog. Del., I. v. 105. If … in any oblique Horizon, there should bee an equinoxe, it could no wise bee in the middle time betwixt the two Solstices.
1726. trans. Gregory’s Astron., I. 418. The true and imaginary Sun will be equally distant from both Equinoxes.
† 3. = Equinoctial line or EQUATOR. Obs.
1579. Fenton, Guicciard., VI. (1599), 252. The Iles of Cape Verde … are distant foureteene degrees from the Equinox.
1697. Dampier, Voy. (1698), I. iv. 90. To the North of the Equinox … in these Seas, I never saw any [Seals].
1728. Earbery, trans. Burnet’s St. Dead, II. 45. The true Fertility that brings Corn to a Masculine Perfection is in Countries far from the Equinox.
† 4. An equinoctial gale. Obs. rare.
1687. Dryden, Hind & P., III. 504. The wind, ’tis true, Was somewhat high, but that was nothing new, Nor more than usual equinoxes blew.
