from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Deviation from perfect circular or spherical form toward elliptic or ellipsoidal form.
  • n. The degree of this deviation.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The condition of being elliptical (flattened from perfect circular or spherical form)
  • n. A measure of this flattening that is a function of the ellipse's equatorial and polar radii

from the GNU version of the Collaborative International Dictionary of English

  • n. Deviation of an ellipse or a spheroid from the form of a circle or a sphere; especially, in reference to the figure of the earth, the difference between the equatorial and polar semidiameters, divided by the equatorial; thus, the ellipticity of the earth is 1/29966.

from The Century Dictionary and Cyclopedia

  • n. The quality of being elliptic; the degree of divergence of an ellipse from the circle; specifically, in reference to the figure of the earth, the difference between the equatorial and polar semi-diameters divided by the equatorial: as, the ellipticity of the earth is .

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the property possessed by a round shape that is flattened at the poles


Sorry, no etymologies found.


  • AFAIU the ellipticity of an egg is due to the pressures from the surrounding egg canal in which it is transported in during its assembly.

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  • He granted that the proposition connected mathematically the inverse square law to the ellipticity of the course of the planets.

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  • (Sometimes circularity is called or confused with ellipticity, but I prefer the former.)

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  • This week, Nathalie Kellens (KULeuven) and Patrick Degryse (Physico-Chemical Geology, KULeuven) classified debris from smithing activities retrieved from the urban and territorial surveys and from the excavations within the city center according to weight, volume, density, mineralogy, chemistry, ellipticity, flatness, position in the smithing hearth and profile of the cakes.

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  • H. Foster's pendulum-experiments, deducing from them an ellipticity for the earth of 1/289 (_Memoirs R.Astr. Soc. _ vii.); corrected for the length of the seconds-pendulum by introducing a neglected element of reduction; and was entrusted, in 1843, with the reconstruction of the standards of length.

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  • So many took part in these singular experiments, which assumed rather the appearance of outdoor sports than of scientific demonstrations, that in a short time we had provided the asteroid with a very large number of little moons, or satellites, of gold, which revolved around it in orbits of various degrees of ellipticity, taking, on the average, about three-quarters of an hour to complete a circuit.

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  • The orbits of Mercury and Mars have an appearance of ellipticity because the sun does not occupy the central point in the diagram.

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  • Further, Descartes was unable to give, or explain the ellipticity of the orbits of planets, and had to assume that there were elliptic vortices.

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  • The ellipticity of the orbit, according to this view, was caused by the planet oscillating about a mean position, -- sinking first into the dense ether, -- then, on account of superior buoyancy, rising into too light a medium.

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  • They were commenced by Tycho Brahé, and completed by Kepler, who made his calculations from Tycho's observations, and based them upon his own great discovery of the ellipticity of the orbits of the planets.

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