sextet vs sextolet

sextet

noun
  • A composition for six voices or instruments. 

  • Any group of six people or things. 

  • A group of six singers or instrumentalists. 

sextolet

noun
  • A double triplet; a group of six equal notes played in the time of four. 

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