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

In our solar system, all the planets orbit around the sun in the ecliptic plane, which is a narrow plane aligned with the sun's equator and direction of rotation. — Keith Cooper, Space.com, 17 Aug. 2026

Because the eclipse also occurs close to Earth’s equator, observers remain inside the moon’s shadow for more than six minutes. — Jamie Carter, Forbes.com, 16 Aug. 2026

And while the Apollo landings stuck close to the lunar equator, landing near the south pole is substantially more complex and requires more powerful vehicles. — Jackie Wattles, CNN Money, 7 Aug. 2026

Because of its rapid spin, Altair is much wider at its equator than at its poles. — Mike Lynch, Twin Cities, 7 June 2026

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

Rhymes for equator

• creator
• curator
• debater
• deflator
• dictator
• dilator
• locator
• piscator
• pronator
• relator
• rotator
• testator

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