sing-song vs soporific

sing-song

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

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

  • An informal gathering involving group singing. 

soporific

adj
  • Boring, dull. 

  • Tending to induce sleep. 

noun
  • Something boring or dull. 

  • Something inducing sleep, especially a drug. 

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