ellipsoid of revolution vs ovoid

ellipsoid of revolution

noun
  • A spheroid; a solid of revolution generated by rotating an ellipse about one of its axes. 

ovoid

noun
  • Something that is oval in shape. 

adj
  • Egg-shaped; shaped like an oval, but more tapered at one end; ovate. 

  • Shaped like an oval. 

How often have the words ellipsoid of revolution and ovoid occurred in a corpus of books? (source: Google Ngram Viewer )