equa·​tor i-ˈkwā-tər How to pronounce equator (audio)
: the great circle of the celestial sphere whose plane is perpendicular to the axis of the earth
: a great circle of the earth or a celestial body that is everywhere equally distant from the two poles and divides the surface into the northern and southern hemispheres
: a circle or circular band dividing the surface of a body into two usually equal and symmetrical parts
: equatorial plane
the equator of a dividing cell

Examples of equator in a Sentence

Recent Examples on the Web Previous moon missions touched down on the moon’s equator. Popular Science, 22 Aug. 2023 The study also found that tropical oceans near the Earth’s equator have become steadily greener overtime. Laura Baisas, Popular Science, 8 Feb. 2024 Enlarge / Visualization of flows in a cut-through of a star’s equator. Jennifer Ouellette, Ars Technica, 22 Aug. 2023 The June solstice marks the exact moment when the noon sun appears directly over the Tropic of Cancer, a line of latitude 23.5 degrees north of Earth’s equator. Justin Grieser, Washington Post, 21 June 2023 The spring equinox, which is also called the March equinox or the vernal equinox, happens when the sun crosses the celestial equator – an imaginary line in the sky above the Earth's equator – going south to north. Victoria Moorwood, The Enquirer, 22 Feb. 2023 This day is known as the June or summer solstice, with a solstice being the twice-yearly astronomical occurrence when the sun is the greatest distance from Earth’s equator. Sarah Zlotnick, Country Living, 12 June 2023 Cassini spacecraft also determined ring material is falling into the planet's equator, which could cause the rings to disappear even faster – in 100 million years. Caitlin O'Kane, CBS News, 8 Nov. 2023 The asteroid, called Bennu, is shaped like a spinning top and spans about one-third of a mile wide at its equator. Will Sullivan, Smithsonian Magazine, 7 Nov. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'equator.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English, from Medieval Latin aequator, literally, equalizer, from Latin aequare

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of equator was in the 14th century

Dictionary Entries Near equator

Cite this Entry

“Equator.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/equator. Accessed 29 Feb. 2024.

Kids Definition


equa·​tor i-ˈkwāt-ər How to pronounce equator (audio)
: an imaginary circle around the earth everywhere equally distant from the north pole and the south pole

Medical Definition


equa·​tor i-ˈkwāt-ər How to pronounce equator (audio) ˈē-ˌ How to pronounce equator (audio)
: a circle or circular band dividing the surface of a body into two usually equal and symmetrical parts especially at the place of greatest width
the equator of the lens of the eye
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