Definitions for

**"Oblate spheroid"**A roughly spherical surface which bulges at its 'equator' and is compressed at its 'poles', such as the surface of a rapidly rotating planet. Mathematically, the surface obtained by rotating an ellipse about its minor axis. As seen from 'above' or 'below' the original minor axis, circular in cross-section, but as seen from the 'side', elliptical in cross-section. Contrasted with a prolate spheroid.

Solid formed by rotating an ellipse about its short axis.

a circular ellipsoid for which cg the symmetry axis is along the smaller semiaxis