posterior vs prat

posterior

noun
  • The hinder parts of the body. 

  • The probability that a hypothesis is true (calculated by Bayes' theorem). 

adj
  • Following in order or in time. 

  • Next to, or facing the main stem or axis. 

  • Relating to or denoting presentation of a fetus in which the rear or caudal end is nearest the cervix and emerges first at birth. 

prat

noun
  • A buttock, or the buttocks; a person's bottom. 

  • A cunning or mischievous trick; a prank, a joke. 

  • The female genitals. 

  • A fool. 

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