impact vs lethargy

impact

verb
  • To stamp or impress onto something. 

  • To collide or strike, the act of impinging. 

  • To significantly or strongly influence or affect; to have an impact on. 

  • To compress; to compact; to press into something or pack together. 

noun
  • A significant or strong influence or effect. 

  • A forced impinging. 

  • The striking of one body against another; collision. 

  • The force or energy of a collision of two objects. 

lethargy

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

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

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