lassitude vs weakness

lassitude

noun
  • Lethargy or lack of energy; fatigue. 

  • Listlessness or languor. 

weakness

noun
  • The condition of being weak. 

  • An inadequate quality; fault 

  • A special fondness or desire. 

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