refrain vs song

refrain

noun
  • The chorus or burden of a song repeated at the end of each verse or stanza. 

  • A much repeated comment, complaint, or saying. 

verb
  • To stop oneself from some action or interference; to abstain. 

  • To abstain from (food or drink). 

song

noun
  • A musical composition with lyrics for voice or voices, performed by singing. 

  • A low price, especially one under the expected value; chiefly in for a song. 

  • A melodious sound made by a bird, insect, whale or other animal. 

  • An object of derision; a laughing stock. 

  • Poetical composition; poetry; verse. 

  • The distinctive sound that a male bird utters to attract a mate or to protect his territory; contrasts with call; also, similar vocalisations made by female birds. 

  • Any musical composition. 

  • The act or art of singing. 

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