serenade vs singalong

serenade

noun
  • An instrumental composition in several movements. 

  • A love song that is sung directly to one's love interest, especially one performed below the window of a loved one in the evening. 

verb
  • To sing or play a serenade for (someone). 

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 serenade and singalong occurred in a corpus of books? (source: Google Ngram Viewer )