deathly vs decedent

deathly

adj
  • Appearing as though dead, or on the verge of death. 

  • Deadly, fatal, causing death. 

  • Extreme. 

adv
  • In a way that resembles death. 

  • Extremely, dreadfully. 

decedent

adj
  • Removing; departing; deceased. 

noun
  • A dead person. 

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