rearward vs retreating

rearward

noun
  • The part that comes last or is situated in the rear; conclusion, wind-up. 

  • The last troop; the rear of an army; a rear guard. 

adv
  • Toward the back or rear of something. 

adj
  • Toward the back or rear of something. 

retreating

noun
  • The act of moving back from something; a retreat. 

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