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Added 9 October 2026

ellipsoid

/ɪˈlɪp.sɔɪd/ noun

noun Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about ellipsoid at Wordnik → Where our words come from →

A surface, all of whose cross sections are elliptic or circular (including the sphere), that generalises the ellipse and in Cartesian coordinates (x, y, z) is a quadric with equation x/a + y/b + z/c = 1.
Such a surface used as a model of the shape of the earth.
Here the geoid is thirty meters below the ellipsoid.

adjective

Shaped like an ellipse; elliptical.
Of or pertaining to an ellipse; elliptic.
Having the tridimensional shape of an ellipse rotated on its long axis.

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