ennui vs tediousness

ennui

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

verb
  • To make bored or listless; to weary. 

tediousness

noun
  • The quality of being tedious; tedium. 

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