Nat vs knothead

Nat

noun

  • A member or supporter of the Scottish National Party. 

  • A member or supporter of the Australian National Party. 

  • A member or supporter of the New Zealand National Party. 

name

  • A diminutive of the female given name Natasha, Natalie, Natalia 

  • A diminutive of the male given name Nathanael, Nathaniel, Nathan 

  • A surname 

knothead

noun

  • A stupid or stubborn person. 

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