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[jee-oid] /ˈdʒi ɔɪd/
an imaginary surface that coincides with mean sea level in the ocean and its extension through the continents.
the geometric figure formed by this surface, an ellipsoid flattened at the poles.
1880-85; < Greek geoeidḗs earthlike. See geo-, -oid
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geoidal, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for geoid
  • Since the geoid is so irregular, geoid undulations cannot be computed directly but must be determined point by point.
British Dictionary definitions for geoid


a hypothetical surface that corresponds to mean sea level and extends at the same level under the continents
the shape of the earth
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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geoid in Science
The hypothetical surface of the Earth that coincides everywhere with mean sea level and is perpendicular, at every point, to the direction of gravity. The geoid is used as a reference surface for astronomical measurements and for the accurate measurement of elevations on the Earth's surface.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for geoid

model of the figure of the Earth-i.e., of the planet's size and shape-that coincides with mean sea level over the oceans and continues in continental areas as an imaginary sea-level surface defined by spirit level. It serves as a reference surface from which topographic heights and ocean depths are measured. The scientific discipline concerned with the precise figure of the Earth and its determination and significance is known as geodesy.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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