disinterest vs lethargy

disinterest

noun
  • An absence of interest (attention or curiosity). 

  • The absence of interest (bias or stake). 

verb
  • To render disinterested. 

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 disinterest and lethargy occurred in a corpus of books? (source: Google Ngram Viewer )