aft vs posterior

aft

adj
  • located at the back of a boat, ship, or airplane 

noun
  • The stern portion of a vessel. 

adv
  • At, near, or towards the stern of a vessel (with the frame of reference within the vessel). 

posterior

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

  • Following in order or in time. 

  • 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 aft and posterior occurred in a corpus of books? (source: Google Ngram Viewer )