rugby ball vs shot put

rugby ball

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

shot put

noun
  • A ball used to perform the action of shot put. 

  • An athletics event where a competitor must hurl a heavy metal orb ("shot") as far as possible. Because of the weight of the ball this is done with a pushing ("putting") motion rather than a throwing motion. 

  • A trial of shot put. 

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