Spheroid

A spheroid is one kind of ellipsoid. It is got by rotating an ellipse about one of its principal axes. This means it is an ellipsoid with two equal semi-diameters.
Spheres are spheroids. Spheroids that are not spheres are either oblate or prolate.
Most celestial objects are oblate spheroids. They usually spin, and as they spin, centrifugal force pulls them into that shape. Few natural objects are prolate spheroids.