circus ring vs oval

circus ring

noun
  • A circular arena in a circus, where the acts are performed. 

oval

noun
  • 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. 

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

adj
  • Of or pertaining to an ovum. 

  • Having the shape of an oval. 

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