septet vs sextuplet

septet

noun
  • A composition for a group of seven musicians. 

  • A group of seven musicians. 

  • A set of seven lines. 

sextuplet

noun
  • A group of six notes played in the time of four, with accents on the first, third and fifth notes. 

  • A group of six notes played in the time of four, with accents on the first and fourth notes; a double triplet. 

  • A group of six objects. 

  • A group of six notes played in the time of four, with an accent only on the first note. 

  • One of a group of six persons or animals born from the same mother during the same birth. 

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