horseling vs wild horse

horseling

noun
  • A young or little horse; foal; pony. 

wild horse

noun
  • An untamed horse. 

  • A feral horse. 

  • A member of the species Equus ferus, sometimes excluding the domesticated horse. 

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