decennary vs frankpledge

decennary

noun
  • A decennium: a period of ten years. 

adj
  • Decennial: of or related to a ten-year period. 

frankpledge

noun
  • 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. 

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

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