oval vs rugby ball

oval

noun
  • A sports field, typically but not exclusively oval in shape. 

  • A thing having such a shape, such as an arena. 

  • In a projective plane, a set of points such that no three are collinear and there is a unique tangent line at each point. 

  • An elongated round shape resembling an egg or ellipse. 

adj
  • Of or pertaining to an ovum. 

  • Having the shape of an oval. 

rugby ball

noun
  • A spheroidal ball designed for the sport of rugby. 

How often have the words oval and rugby ball occurred in a corpus of books? (source: Google Ngram Viewer )