[ee-kwuh-nok-shuh l, ek-wuh-]


pertaining to an equinox or the equinoxes, or to the equality of day and night.
pertaining to the celestial equator.
occurring at or about the time of an equinox.
Botany. (of a flower) opening regularly at a certain hour.


Origin of equinoctial

1350–1400; Middle English < Latin aequinoctiālis pertaining to the equinox. See equinox, -al1
Related formsin·ter·e·qui·noc·tial, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for equinoctial

equator, equinoctial

Examples from the Web for equinoctial

Historical Examples of equinoctial

  • For the Equinoctial Circle does not cut the Zodiac at right angles.

    The Non-Christian Cross

    John Denham Parsons

  • An equinoctial gale was raging, or rather had been raging all day.

    The First Violin

    Jessie Fothergill

  • The "Ranger" had encountered an equinoctial gale in its worst form.

  • I don't know if you remember that equinoctial gale that blew about the 18th or 19th.

    My New Curate

    P.A. Sheehan

  • They will in all probability be caught in the equinoctial gales.

    Flora Lyndsay

    Susan Moodie

British Dictionary definitions for equinoctial



relating to or occurring at either or both equinoxes
(of a plant) having flowers that open and close at specific regular times
astronomy of or relating to the celestial equator


a storm or gale at or near an equinox
another name for celestial equator

Word Origin for equinoctial

C14: from Latin aequinoctiālis concerning the equinox
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

equinoctial in Science


[ē′kwə-nŏkshəl, ĕk′wə-]


Relating to an equinox.
Relating to the celestial equator.


See celestial equator.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.