equinoctial

• (archaic) æquinoctial

From Latin aequinoctiālis, from aequinoctium + -alis.

• (Received Pronunciation) IPA^(key): /ɛkwɪˈnɒkʃl̩/
• (General American) IPA^(key): /ˌi.kwəˈnɒk.ʃəl/, /ˌɛ.kwəˈnɒk.ʃəl/

equinoctial (not comparable)

1. (astronomy) Of or relating to the spring or autumnal equinox.

   an equinoctial gale or storm, i.e. one happening at or near the time of the equinox, in any part of the world

2. (astronomy) Of or relating to the celestial equator.
3. (uncommon) Equatorial: Of or relating to the equator of the Earth.

• (relating to the equinox): (uncommon) equinoctal, (archaic) equinoxial
• (relating to the terrestrial equator): See equatorial

equinoctial (plural equinoctials)

1. The great circle midway between the celestial poles; the celestial equator.
   • 1621, Democritus Junior [pseudonym; Robert Burton], The Anatomy of Melancholy, Oxford: Printed by Iohn Lichfield and Iames Short, for Henry Cripps, OCLC 216894069; The Anatomy of Melancholy: […], 2nd corrected and augmented edition, Oxford: Printed by John Lichfield and James Short, for Henry Cripps, 1624, OCLC 54573970, partition III, section 2, member 1, subsection ii:

     The scorching beams under the equinoctial, or extremity of cold within the circle Arctic, […] cannot avoid or expel this heat, fury, and rage of mortal men.

2. (rare) The terrestrial equator.
   • 1645, James Howell, “England’s Tears, for the Present Wars, which for the Nature of the Quarrel, the Quality of the Strength, the Diversity of Battels, Skirmishes, Encounters, and Sieges, (Happened in so Short a Compasse of Time) Cannot be Parallel’d in Any Precedent Age”, in ΔΕΝΔΡΟΛΟΓΊΑ [DENDROLOGIA]: Dodona’s Grove, or The Vocall Forrest. The Third Edition More Exact and Perfect than the Former; with the Addition of Two Other Tracts: viz. Englands Tears for the Present Wars. And The Pre-eminence of Parlements, 3rd edition, Cambridge: Printed by R. D. for Humphrey Moseley, and are to be sold at his shop at the Prince's Arms in S. Pauls Church-yard, OCLC 931321630, page 189:

     O conſider my caſe, moſt blisfull Queen, […] Diſpell thoſe Clouds which hover 'twixt my King and his higheſt Counſell, […] that my great Law-making Court be forced to turn no more to polemicall Committees, […] but that they may come again to the old Parliamentary Rode, To the path of their Predeceſſours, to conſult of means how to ſweep away thoſe Cobwebs that hang in the Courts of Juſtice, and to make the Laws run in their right Channell; to retrench exceſſive fees, and finde remedies for the future, that the poor Client be not ſo peeled by his Lawyer, and made to ſuffer by ſuch monſtrous delays, that one may go from one Tropick to the other, and croſſe the Equinoctiall twenty times, before his ſute be done; […]

• “equinoctial” in The Oxford English Dictionary, 2nd edition, Oxford: Clarendon Press, 1989, →ISBN.