duple vs twosome

duple

adj
  • Double. 

  • Having two beats in each foot. 

  • Having two beats, or a multiple of two beats, in each measure. 

twosome

adj
  • Twofold; double. 

  • Performed by two individuals. 

  • Being or constituting a pair; two. 

noun
  • A group of two; a pair; a couple; a group of two distinct individuals or components. 

  • A dance for two people. 

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