internecine vs lethal

internecine

adj
  • Mutually destructive; most often applied to warfare. 

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

lethal

adj
  • Of, pertaining to, or causing death; deadly; mortal; fatal. 

noun
  • One of the higher alcohols of the paraffine series obtained from spermaceti as a white crystalline solid. 

  • An allele that causes the death of the organism that carries it. 

  • Any weapon that causes death. 

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