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[ih-lip-soid] /ɪˈlɪp sɔɪd/
Geometry. a solid figure all plane sections of which are ellipses or circles. Typical equation: (x 2 / a 2) + (y 2 / b 2) + (z 2 / c 2) = 1.
1715-25; < French ellipsoïde. See ellipse, -oid Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for ellipsoid
  • The geoid height is the separation between the ellipsoid and the geoid with the surface represented as mean sea level.
British Dictionary definitions for ellipsoid


  1. a geometric surface, symmetrical about the three coordinate axes, whose plane sections are ellipses or circles. Standard equation: x²/a² + y²/b² + z²/c² = 1, where ±a, ±b, ±c are the intercepts on the x-, y-, and z- axes
  2. a solid having this shape: the earth is an ellipsoid
Derived Forms
ellipsoidal (ɪlɪpˈsɔɪdəl; ˌɛl-) adjective
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 ellipsoid

1721; see ellipse + -oid. From 1861 as an adjective (earlier adjective was ellipsoidal).

Online Etymology Dictionary, © 2010 Douglas Harper
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ellipsoid in Science
A three-dimensional geometric figure resembling a flattened sphere. Any cross section of an ellipsoid is an ellipse or circle. An ellipsoid is generated by rotating an ellipse around one of its axes.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for ellipsoid

closed surface of which all plane cross sections are either ellipses or circles. An ellipsoid is symmetrical about three mutually perpendicular axes that intersect at the centre

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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