enervation vs lassitude

enervation

noun
  • State of being enervated; debility. 

  • Act of enervating; debilitation. 

lassitude

noun
  • Lethargy or lack of energy; fatigue. 

  • Listlessness or languor. 

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