equator

American  

[ih-kwey-ter] / ɪˈkweɪ tər /

noun

1. the great circle on a sphere or heavenly body whose plane is perpendicular to the axis, equidistant everywhere from the two poles of the sphere or heavenly body.

2. the great circle of the earth that is equidistant from the North Pole and South Pole.

3. a circle separating a surface into two congruent parts.

4. celestial equator.

---

equator British  

/ ɪˈkweɪtə /

noun

1. the great circle of the earth with a latitude of 0°, lying equidistant from the poles; dividing the N and S hemispheres

2. a circle dividing a sphere or other surface into two equal symmetrical parts

3. See magnetic equator

4. astronomy See celestial equator

---

equator Scientific  

/ ĭ-kwā′tər /

1. An imaginary line forming a great circle around the Earth's surface, equidistant from the poles and in a plane perpendicular to the Earth's axis of rotation. It divides the Earth into the Northern and Southern hemispheres and is the basis from which latitude is measured.

2. A similar circle on the surface of any celestial body.

3. The celestial equator.

---

equator Cultural  

1. An imaginary circle around the Earth, equidistant from the North Pole and South Pole.

---

Etymology

Origin of equator

1350–1400; Middle English < Medieval Latin aequātor, Latin: equalizer (of day and night, as when the sun crosses the equator). See equate, -tor

Example Sentences

"Instead of even spreading, these slow-moving impacts would create a deposit rather than a crater. And they are centered on the equator as predicted from modeling material spun off the primary."

From Science Daily • Mar. 8, 2026

The site's position close to the equator was more suitable for some missions than the Russian-operated spaceport in Baikonur, Kazakhstan.

From Barron's • Feb. 18, 2026

Notice that this map stretches things out vertically near the equator and horizontally near the poles.

From Slate • Jan. 21, 2026

These are determined by Earth's tilt and the sun's position over the equator.

From BBC • Jan. 10, 2026

I didn’t think it would matter which copy of his hometown I went to, so I selected one at random, near the equator.

From "Ready Player One: A Novel" by Ernest Cline

Related Words

• ring
• sphere