foal vs racehorse

foal

noun
  • A young horse or other equine, especially just after birth or less than a year old. 

  • A young boy who assisted the headsman by pushing or pulling the tub. 

verb
  • To give birth to (a foal); to bear offspring. 

racehorse

noun
  • A horse that competes in races. 

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