pivotal vs posterior

pivotal

adj
  • Of, relating to, or being a pivot. 

  • Being of crucial importance; central, key. 

posterior

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. 

noun
  • The hinder parts of the body. 

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

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