big cat vs wild cat

big cat

noun
  • Used other than figuratively or idiomatically: see big, cat. 

  • Any large feline animal, especially one of the Panthera genus, including tigers, lions, jaguars and leopards. 

wild cat

noun
  • A feral cat. 

  • An undomesticated felid, as tigers or lions. 

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