madrigal vs villanelle

madrigal

noun
  • A short poem, often pastoral, and suitable to be set to music. 

  • A song for a small number of unaccompanied voices; from 13th century Italy. 

  • A polyphonic song for about six voices, from 16th century Italy. 

villanelle

noun
  • A type of poem, consisting of five tercets and one quatrain, with only two rhymes. 

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