equinoctial

American  

[ee-kwuh-nok-shuhl, ek-wuh-] / ˌi kwəˈnɒk ʃəl, ˌɛk wə- /

adjective

1. pertaining to an equinox or the equinoxes, or to the equality of day and night.

2. pertaining to the celestial equator.

3. occurring at or about the time of an equinox.

4. Botany. (of a flower) opening regularly at a certain hour.

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noun

1. celestial equator.

2. equinoctial storm.

equinoctial British  

/ ˌiːkwɪˈnɒkʃəl /

adjective

1. relating to or occurring at either or both equinoxes

2. (of a plant) having flowers that open and close at specific regular times

3. astronomy of or relating to the celestial equator

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noun

1. a storm or gale at or near an equinox

2. another name for celestial equator

equinoctial Scientific  

/ ē′kwə-nŏk′shəl,ĕk′wə- /

1. Relating to an equinox.

2. Relating to the celestial equator.

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1. See celestial equator

Other Word Forms

Derived Forms

• interequinoctial
  adjective

Etymology

Origin of equinoctial

1350–1400; Middle English < Latin aequinoctiālis pertaining to the equinox. See equinox, -al ¹

Explanation

If something happens right around the time of an equinox — the two days each year when day and night are of equal length — you can describe it as equinoctial. If your birthday falls on the spring equinox, you can call it equinoctial, and you could also call the fall hurricanes in your coastal town equinoctial storms. In either case, the thing that makes something equinoctial is its proximity to the dates in the spring and fall when the Earth isn't tipped toward or away from the sun but is positioned so the equator lines up with it. The Latin roots are aequus, "equal," and nox, "night."