deathful vs pernicious

deathful

adj
  • Involving the danger of death; fatal, deadly. 

  • Subject to death; mortal. 

  • Resembling or pertaining to death; deathly. 

pernicious

adj
  • Causing death or injury; deadly. 

  • Causing much harm in a subtle way. 

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