lethargic vs prepatent

lethargic

adj
  • indifferent, apathetic 

  • sluggish, slow 

prepatent

adj
  • Prior to the existence of a legal patent. 

  • Before symptoms (especially of infection) become manifest. 

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