ennui vs sluggishness

ennui

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

verb
  • To make bored or listless; to weary. 

sluggishness

noun
  • The property of being sluggish, unable or unwilling to act quickly. 

  • The state of economic decline, inactivity, slow or subnormal growth. 

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