Acheron vs hellfire

Acheron

name
  • Hell 

  • A language of Sudan. 

  • A river in the infernal regions; also, the infernal regions themselves. By some of the English poets, it was supposed to be a flaming lake or gulf. 

hellfire

noun
  • The fire of Hell. 

  • Fire produced by the Devil, or a similar supernatural creature connected to Hell. 

  • A fire that burns with unusual heat or ferocity. 

intj
  • hell; damn; blast 

adj
  • Of or relating to a violent, apocalyptic and ultimate day of reckoning and judgment; usually characterizing a form of Christian preaching. 

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