aft vs retral

aft

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

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

noun
  • The stern portion of a vessel. 

retral

adj
  • back; posterior 

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