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

To really level up your observing, a telescope will offer a good view of Jupiter’s Great Red Spot, the enormous storm swirling south of its equator. —Carlyn Kranking, Smithsonian Magazine, 5 Dec. 2024

Phobos is roughly 157 times smaller in diameter than Earth’s Moon, according to NASA, and orbits the Mars nearly at its equator. —James Powel, USA TODAY, 1 Nov. 2024

With time, the disintegrated asteroid pieces would have assembled into a ring shape around our planet’s equator. —Margherita Bassi, Smithsonian Magazine, 19 Sep. 2024

Arthropleura lived between 290 million and 346 million years ago, skittering around the Earth’s tropical equator alongside other massive arthropods like the two-foot-long scorpion Pulmonoscorpius. —Olatunji Osho-Williams, Smithsonian Magazine, 22 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