[f. ELLIPSE + -OID.]

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  A.  sb.

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  1.  A solid of which all the plane sections through one of the axes are ellipses, and all other sections ellipses or circles. Formerly in narrower sense: A solid generated by the revolution of an ellipse round one of its axes; now called ellipsoid of revolution.

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a. 1721.  Keill, trans. Maupertuis’ Diss. (1734), 7. The Earth must be an Ellipsoid whose Equatorial Diameter is to its Axis as √289 to √288.

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1787.  Phil. Trans., LXXVII. 202. Ellipsoids of different degrees of oblateness.

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1831.  Brewster, Optics, vi. 55. A meniscus whose convex surface is part of an ellipsoid.

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1871.  B. Stewart, Heat, § 281. The isothermal surfaces are ellipsoids.

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1879.  C. Niven (title), On the Conduction of Heat in Ellipsoids of Revolution.

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  2.  ? A figure approximately elliptical.

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1837.  Whewell, Hist. Induc. Sc. (1857), II. 59. An eccentric ellipsoid; that is a figure resembling an ellipse.

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  B.  adj. = next.

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1861.  Hulme, trans. Moquin-Tandon, II. VI. i. 313. They [the eggs] are elipsoid or oval.

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1870.  Hooker, Stud. Flora, 142. Styles erect or spreading, pollen ellipsoid.

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