harmless vs internecine

harmless

adj
  • Incapable of causing harm or danger; safe. 

  • Not intended to harm; inoffensive. 

internecine

adj
  • Mutually destructive; most often applied to warfare. 

  • Characterized by struggle within a group, usually applied to an ethnic or familial relationship. 

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