father-slayer vs parricide

father-slayer

noun
  • One who kills or murders one's father; a patricide 

parricide

noun
  • Someone who kills a relative, especially a parent. 

  • The killing of a relative, especially a parent. 

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

  • Someone who commits treason. 

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