equator definition | Dictionary.com

e⋅qua⋅tor

[i-kwey-ter]

–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.

Origin:
1350–1400; ME < ML aequātor, L: equalizer (of day and night, as when the sun crosses the equator). See equate, -tor

celestial equator

–noun Astronomy, Navigation.

the great circle of the celestial sphere, lying in the same plane as the earth's equator.

Also called equator, equinoctial, equinoctial circle, equinoctial line.

Origin:
1870–75

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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Link To equator

e·qua·tor (ĭ-kwā'tər)

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n.

1. The imaginary great circle around the earth's surface, equidistant from the poles and perpendicular to the earth's axis of rotation. It divides the earth into the Northern Hemisphere and the Southern Hemisphere.
2. A similar great circle drawn on the surface of a celestial body at right angles to the axis of rotation.
The celestial equator.
A circle that divides a sphere or other surface into congruent parts.

[Middle English, from Medieval Latin aequātor (diēī et noctis), equalizer (of day and night), from Latin aequāre, to equalize; see equate.]

The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Equator

E*qua"tor\, n. [L. aequator one who equalizes: cf. F. ['e]quateur equator. See Equate.]

1. (Geog.) The imaginary great circle on the earth's surface, everywhere equally distant from the two poles, and dividing the earth's surface into two hemispheres.

2. (Astron.) The great circle of the celestial sphere, coincident with the plane of the earth's equator; -- so called because when the sun is in it, the days and nights are of equal length; hence called also the equinoctial, and on maps, globes, etc., the equinoctial line.

Equator of the sun or of a planet (Astron.), the great circle whose plane passes through through the center of the body, and is perpendicular to its axis of revolution.

Magnetic equator. See Aclinic.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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Language Translation for : equator

Spanish: ecuador,

German: der Äquator,

Japanese: 赤道

More Translations »

equator

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

equator

c.1391, from M.L. æquator diei et noctis "equalizer of day and night" (when the sun is on the celestial equator, twice annually, day and night are of equal length), from L. æquare "make equal, equate." Sense of "celestial equator" is earliest, extension to "terrestrial line midway between the poles" first recorded in Eng. 1612.

Main Entry: equa·tor
Pronunciation: i-'kwAt-&r, 'E-"
Function: noun
1 : a circle or circular band dividing the surface of a body into twousually equal and symmetrical parts especially at the place of greatest width equator of the lens of the eye>
2 : EQUATORIAL PLANE equator of the cell —R. P. Levine>

equator (ĭ-kwā'tər) Pronunciation Key

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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.
A similar circle on the surface of any celestial body.
The celestial equator.

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