acedia vs lassitude

acedia

noun
  • Apathy; a lack of care or interest; indifference. 

  • Spiritual or mental sloth. 

  • Boredom. 

lassitude

noun
  • Listlessness or languor. 

  • Lethargy or lack of energy; fatigue. 

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