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equinox (n.)[equinox 词源字典]: c. 1400, "point at which the sun crosses the earth's equator, making day and night of equal length everywhere," from Old French equinoce (12c.) or directly from Medieval Latin equinoxium "equality of night (and day)," from Latin aequinoctium, usually in plural, dies aequinoctii "the equinoxes," from aequus "equal" (see equal (adj.)) + nox (genitive noctis) "night" (see night). The Old English translation was efnniht. Related: Equinoctial.[equinox etymology, equinox origin, 英语词源]
equinoctial: "Happening at or near the time of an equinox", Late Middle English (in the sense 'relating to equal periods of day and night'): via Old French from Latin aequinoctialis, from aequinoctium (see equinox).