septenarius vs septuplet

septenarius

noun
  • A verse having seven metrical feet. 

septuplet

noun
  • A group of seven, particularly (music) a tuplet of seven notes. 

  • One of a group of seven, particularly one of seven babies born at the same birth. 

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