ennui vs lifelessness

ennui

noun
  • A gripping listlessness or melancholia caused by boredom; depression. 

verb
  • To make bored or listless; to weary. 

lifelessness

noun
  • The property of being lifeless, the lack of apparent animation. 

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