ellipticity

[ ih-lip-tis-i-tee, el-ip-, ee-lip- ]

/ ɪ lɪpˈtɪs ɪ ti, ˌɛl ɪp-, ˌi lɪp- /

the degree of divergence of an ellipse from a circle.

Origin of ellipticity

1745–55; elliptic- (see elliptical) + -ity

This fraction is denominated the ellipticity of the earth,—being the excess of the equatorial over the polar diameter.

Letters on Astronomy |Denison Olmsted
The form of our globe, which is that of an oblate spheroid with an ellipticity of about 1⁄299.

The Sailor's Word-Book |William Henry Smyth
The specific difference in the new family, denoted in the general sketch by b, is this ellipticity of the equator.

Darwin and Modern Science |A.C. Seward and Others
We may consider this spheroid to be that of the earth, the ellipticity being greatly exaggerated.

Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 3 |Various

Hence it is plain that Clairaut's theorem furnishes a practical method for determining the value of the earth's ellipticity.

Biographies of Distinguished Scientific Men |Francois Arago

ellipticity

/ (ɪlɪpˈtɪsɪtɪ, ˌɛl-) /

the degree of deviation from a circle or sphere of an elliptical or ellipsoidal shape or path, measured as the ratio of the major to the minor axes