lassitude vs prostration

lassitude

noun
  • Lethargy or lack of energy; fatigue. 

  • Listlessness or languor. 

prostration

noun
  • The condition of being prostrated, as from heat; complete loss of strength. 

  • A part of the ordination of Catholic and Orthodox priests. 

  • The act or condition of prostrating oneself (lying flat), as a sign of humility. 

  • A reverential bow performed in Middle Eastern cultures. 

  • Being laid face down (prone). 

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