choir vs sing-song

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. 

sing-song

noun
  • An informal gathering involving group singing. 

  • A kind of verse with a simple, song-like rhythm. 

adj
  • Like a piece of sing-song; simple and melodic, song-like. 

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