Cat vs Kitty

Cat

name

  • A diminutive of the female given names Catherine or Caitlin. 

noun

  • A Catalina flying boat. 

  • A piece of heavy machinery, such as a backhoe, of the Caterpillar brand. 

Kitty

name

  • A diminutive of Katherine and related female given names. 

  • A generic name for a cat. 

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