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

The part of Wyoming where the new species emerged was located in low latitudes near the prehistoric equator around 230 million years ago. —Newsweek, 8 Jan. 2025

Perseverance, which touched down in 2021, has been exploring a 28-mile-wide basin north of the Martian equator that scientists think was home to an ancient river delta. —Denise Chow, NBC News, 7 Jan. 2025

Sunspots are mostly close to the sun's equator during solar maximum, which can be observed right now by anyone with a pair of solar eclipse glasses. —Jamie Carter, Forbes, 28 Dec. 2024

Doomed from the start Phobos completes an orbit around the Martian equator every 7.6 hours, or three times a day, and is about 3,700 miles (6,000 kilometers) from the surface of the red planet. —Ashley Strickland, CNN, 31 Oct. 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