malignant vs mortiferous

malignant

adj
  • Tending to produce death; threatening a fatal issue. 

  • Harmful, malevolent, injurious. 

noun
  • A deviant; a person who is hostile or destructive to society. 

mortiferous

adj
  • Causing physical death; deadly, fatal, lethal. 

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