sing-song vs singalong

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. 

singalong

noun
  • A gathering of people who sing together 

adj
  • designed to allow or encourage the audience to sing along 

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