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equator

[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.
Origin
1350-1400
1350-1400; Middle English < Medieval Latin aequātor, Latin: equalizer (of day and night, as when the sun crosses the equator). See equate, -tor
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for equators

equator

/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
4.
(astronomy) See celestial equator
Word Origin
C14: from Medieval Latin (circulus) aequātor (diei et noctis) (circle) that equalizes (the day and night), from Latin aequāre to make equal
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for equators

equator

n.

late 14c., from Medieval Latin aequator 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), agent noun from Latin aequare "make equal" (see equate). Sense of "celestial equator" is earliest, extension to "terrestrial line midway between the poles" first recorded in English 1610s.

Online Etymology Dictionary, © 2010 Douglas Harper
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equators in Science
equator
  (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.


The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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equators in Culture

equator definition


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

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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