filicide vs frankpledge

filicide

noun
  • The killing of one's own child. 

  • A person who kills their own child. 

frankpledge

noun
  • A form of collective suretyship and punishment under English law among the members of a tithing. 

  • A decener: a member of a tithing bound in frankpledge. 

  • Any group so similarly answerable for the conduct of all its members and liable for collective punishment. 

  • The tithing itself. 

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