chirl vs choir

chirl

noun
  • A kind of musical warble. 

verb
  • To emit a low sound; to warble. 

choir

noun
  • A group of people who sing together; a company of people who are trained to sing together. 

  • The part of a church where the choir assembles for song. 

  • One of the nine ranks or orders of angels. 

  • Set of strings (one per note) for a harpsichord. 

verb
  • To sing in concert. 

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