indiscernible vs lethetic

indiscernible

adj
  • Not capable of being discerned, of being perceived. 

  • Not capable of being distinguished from something else. 

noun
  • Something which is incapable of being discerned. 

lethetic

adj
  • Failing to mirror reality, purely escapist or nonsensical. 

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