inanition vs lethargy

inanition

noun
  • A state of advanced lack of adequate nutrition, food, or water or a physiological inability to utilize them, with resulting weakness. 

  • A spiritual emptiness or lack of purpose or will to live, akin to the Existentialist Philosophy state of "nausea". 

  • The act of removing the contents of something; the state of being empty. 

lethargy

noun
  • A state of extreme torpor or apathy, especially with lack of emotion, energy or enthusiasm; (loosely) sluggishness, laziness. 

  • A condition characterized by extreme fatigue or drowsiness, deep unresponsiveness, or prolonged sleep patterns. 

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