ellipsoidal : Idioms & Phrases

• noun a shape that is generated by rotating an ellipse around one of its axes
  spheroid.
  
  • it looked like a sphere but on closer examination I saw it was really a spheroid

WordNet

• 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.

Webster 1913