equine vs hobby horse

equine

noun
  • Any horse or horse-like animal, especially one of the genus Equus. 

adj
  • Of or relating to any member or members of the genus Equus. 

  • Of or relating to a horse or horses. 

hobby horse

noun
  • The Irish hobby, an extinct breed of horse. 

  • A topic about which someone loves to talk at great length. 

  • A child's toy consisting of a (usually wooden or cloth) horse's head mounted on a stick. 

  • A puppet-like costume used in some traditional dances and festivals that gives its wearer the appearance of a man on horseback. 

  • An early bicycle with no pedals or brakes; a draisienne. 

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