bebop vs refrain

bebop

verb
  • To participate in bebop jazz, such as by dancing in a way associated with the genre. 

  • To walk in an easygoing, carefree manner. 

noun
  • An early form of modern jazz played by small groups and featuring driving rhythms and complex, often dissonant harmonies. 

refrain

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

  • To abstain from (food or drink). 

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

  • A much repeated comment, complaint, or saying. 

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