extermination vs parricide

extermination

noun
  • The act of exterminating; total destruction or eradication 

  • Elimination. 

parricide

noun
  • The killing of a ruler, or other authority figure; treason. 

  • The killing of a relative, especially a parent. 

  • Someone who kills a relative, especially a parent. 

  • Someone who commits treason. 

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