# Ellipsoid

## El*lip"soid

(?), n. [Ellipse + -oid: cf. F. ellipsoide.] (Geom.) A solid, all plane sections of which are ellipses or circles. See Conoid, n., 2 (a).
[1913 Webster]

The ellipsoid has three principal plane sections, a, b, and c, each at right angles to the other two, and each dividing the solid into two equal and symmetrical parts. The lines of meeting of these principal sections are the axes, or principal diameters of the ellipsoid. The point where the three planes meet is the center.
[1913 Webster]

Ellipsoid of revolution, a spheroid; a solid figure generated by the revolution of an ellipse about one of its axes. It is called a prolate spheroid, or prolatum, when the ellipse is revolved about the major axis, and an oblate spheroid, or oblatum, when it is revolved about the minor axis.

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## El`lip*soi"dal

(?), } a. Pertaining to, or shaped like, an ellipsoid; as, ellipsoid or ellipsoidal form.

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## El*lip"tic*al

(?), } a. [Gr. : cf. F. elliptique. See Ellipsis.] 1. Of or pertaining to an ellipse; having the form of an ellipse; oblong, with rounded ends.
[1913 Webster]

The planets move in elliptic orbits.
Cheyne.
[1913 Webster]

The billiard sharp who any one catches,
His doom's extremely hard --
He's made to dwell
In a dungeon cell
On a spot that's always barred.
And there he plays extravagant matches
In fitless finger-stalls
On a cloth untrue
With a twisted cue
And elliptical billiard balls!

Gilbert and Sullivan (The Mikado: The More Humane Mikado Song)

2. Having a part omitted; as, an elliptical phrase.
[1913 Webster]

3. leaving out information essential to comprehension; so concise as to be difficult to understand; obscure or ambiguous; -- of speech or writing; as, an elliptical comment.
[PJC]

Elliptic chuck. See under Chuck. -- Elliptic compasses, an instrument arranged for drawing ellipses. -- Elliptic function. (Math.) See Function. -- Elliptic integral. (Math.) See Integral. -- Elliptic polarization. See under Polarization.
[1913 Webster]

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Sun 13th June 2021