courser vs troop horse

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. 

troop horse

noun
  • A cavalry horse. 

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