courser vs racer

courser

noun
  • A racehorse or a charger. 

  • A person who practises coursing. 

  • Any of several species of bird in the genera Cursorius or Rhinoptilus of the family Glareolidae. 

  • A dog used for coursing. 

  • A stone used in building a course. 

  • A hunter. 

racer

noun
  • A racehorse. 

  • Someone who takes part in a race. 

  • Any of several genera of colubrid snakes. 

  • A video game involving racing of any kind. 

  • An animal known for its fast speed, or suitable for racing; applied especially to a number of North American snakes, certain kinds of lake trout, etc. 

  • A vehicle or other device used for, or designed specifically for, racing. 

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