equatorial

adjective

equa·​to·​ri·​al ˌē-kwə-ˈtȯr-ē-əl How to pronounce equatorial (audio)
ˌe-kwə-
1
a
: of, relating to, or located at the equator or an equator
also : being in the plane of the equator
a satellite in equatorial orbit
b
: of, originating in, or suggesting the region around the geographic equator
2
a
: being or having a support that includes two axles at right angles to each other with one parallel to the earth's axis of rotation
an equatorial telescope mount
b
: extending in a direction essentially in the plane of a cyclic structure (as of cyclohexane)
equatorial hydrogens
compare axial

Examples of equatorial in a Sentence

a lush equatorial rain forest that is threatened by rampant development
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Another factor is the Quasi-Biennial Oscillation (QBO), a 24–28-month cycle in which equatorial winds shift east to west. Joe Edwards, MSNBC Newsweek, 29 Aug. 2025 From the rainforests of Central and South America to the savannas of northern Australia, the world’s equatorial regions are home to thousands of unique bird species, from macaws to toucans to hummingbirds, who thrive in hot and humid environments. Lex Harvey, CNN Money, 13 Aug. 2025 Other red supergiants in binary or multiple star systems display equatorial rings in their circumstellar material driven by the orbital interactions of a companion star. Keith Cooper, Space.com, 13 Aug. 2025 In today’s world, glacial ice can persist in equatorial regions such as the Andes and Indonesia, but only on mountainous slopes several miles above sea level. Laura Poppick july 22, Literary Hub, 22 July 2025 See All Example Sentences for equatorial

Word History

First Known Use

1664, in the meaning defined at sense 1a

Time Traveler
The first known use of equatorial was in 1664

Cite this Entry

“Equatorial.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/equatorial. Accessed 11 Sep. 2025.

Kids Definition

equatorial

adjective
equa·​to·​ri·​al ˌē-kwə-ˈtōr-ē-əl How to pronounce equatorial (audio)
ˌek-wə-,
-ˈtȯr-
1
: of, relating to, or located at the equator
2
: of, originating in, or suggesting the region around the equator
equatorial heat

Medical Definition

equatorial

adjective
equa·​to·​ri·​al ˌē-kwə-ˈtōr-ē-əl How to pronounce equatorial (audio) ˌek-wə- How to pronounce equatorial (audio)
-ˈtȯr-
1
: of, located at, or relating to an equator
equatorial diameter
2
: extending in a direction essentially in the plane of a cyclic structure (as of cyclohexane)
equatorial hydrogen atoms
compare axial sense 2b

More from Merriam-Webster on equatorial

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