equator

noun

equa·​tor i-ˈkwā-tər 

ˈē-ˌkwā-

1

: the great circle of the celestial sphere whose plane is perpendicular to the axis of the earth

2

: 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

3

a

: a circle or circular band dividing the surface of a body into two usually equal and symmetrical parts

b

: equatorial plane

the equator of a dividing cell

4

: great circle

Examples of equator in a Sentence

Recent Examples on the Web

For a long period ending only about 12,000 years ago, our planet withstood a series of harsh ice ages that saw global temperatures fluctuate, sea levels rise and fall as glaciers melted and re-froze, and plant and animal life shift from the poles toward the warmer equator. —Christian Thorsberg, Smithsonian Magazine, 14 June 2024

The thin yet widespread layers of water frost were discovered atop three of Mars' Tharsis volcanoes, located on a plateau at the planet's equator, according to a new study published in the journal Nature Geoscience. —Leah Sarnoff, ABC News, 10 June 2024

One way to do that is to create a series of particle accelerator stations in orbit around the Sun’s equator. —Paul Sutter, Ars Technica, 16 Apr. 2024

This equinox happens when the sun crosses the celestial equator, an imaginary line above the Earth’s equator, going from south to north. —Victoria Moorwood, The Enquirer, 20 Mar. 2024

Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing equator

• celestial equator
• magnetic equator
• the equator

Kids Definition

equator

noun

equa·​tor i-ˈkwāt-ər 

ˈē-ˌkwāt-

: an imaginary circle around the earth everywhere equally distant from the north pole and the south pole

Medical Definition

equator

noun

equa·​tor i-ˈkwāt-ər  ˈē-ˌ 

1

: 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

2

: equatorial plane