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

They were first spotted back in 1997 by NASA's Pathfinder mission from just north of Mars' equator. —Sharmila Kuthunur, Space.com, 13 Feb. 2025

Saturn’s other moons orbit over its equator, so the material from this one would likely have wound up in a similar configuration as well. —Phil Plait, Scientific American, 23 Jan. 2025

The planets in our solar system orbit the sun in roughly the same plane, known as the ecliptic, which is tilted relative to Earth's equator by about 23.5 degrees. —Justin Gest, Newsweek, 20 Jan. 2025

Those storms tended to start at the planet's poles, then move toward its equator. —Paul Smaglik, Discover Magazine, 7 Jan. 2025

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