feebleness vs lassitude

feebleness

noun
  • The quality or state of being feeble; debility; infirmity. 

lassitude

noun
  • Listlessness or languor. 

  • Lethargy or lack of energy; fatigue. 

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