septette vs septuplet

septette

noun
  • A musical composition for seven instruments or seven voices; a septuor. 

  • A set of seven persons or objects. 

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 septette and septuplet occurred in a corpus of books? (source: Google Ngram Viewer )