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

• 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."

Example Sentences

Additional plotting revealed that alignment of other stones had pinpointed equinoctial positions of the rising and setting sun and moon, enabling Stonehenge observers to determine accurately the first dav of both spring and fall.

From Time Magazine Archive

An ecumenical rundown of all the world's most important places of worship, from the equinoctial siting at Stonehenge to the bland Meditation Room at the United Nations.

From Time Magazine Archive

Hardly had the equinoctial orgy begun, when it turned as bleak as a midwinter blizzard.

From Time Magazine Archive

One bright and fragrant spring day—as if on a wild equinoctial whim—Holmes suggested that Minnie invite her sister to Chicago to see the world’s fair, at his expense.

From "The Devil in the White City" by Erik Larson

Because it is symbolic of two annual periods which mainly affect the condition of man upon this globe—the two equinoctial crossings by the sun.

From Religion In The Heavens Or, Mythology Unveiled in a Series of Lectures by Mitchell, Logan