Equinox \E"qui*nox\, n. [OE. equinoxium, equenoxium, L. aequinoctium; aequus equal + nox, noctis, night: cf. F. ['e]quinoxe. See Equal, and Night.]

1. The time when the sun enters one of the equinoctial points, that is, about March 21 and September 22. See Autumnal equinox, Vernal equinox, under Autumnal and Vernal.

When descends on the Atlantic The gigantic Stormwind of the equinox. --Longfellow.

2. Equinoctial wind or storm. [R.]

--Dryden.

Source: Webster's Revised Unabridged Dictionary (1913)