a cappella vs singsong

a cappella

adj
  • Related to a form of purely vocal music mostly associated with American college performance groups. 

  • Singing solely or mainly without instrumental accompaniment. 

adv
  • In a manner of a choir with no instrumental accompaniment; literally, "in the style of the (Sistine) Chapel (in Rome)", such as a musical Mass done a cappella. 

noun
  • A vocal performance with no instrumental accompaniment. 

singsong

adj
  • Like a piece of singsong; simple and melodic, varying in pitch (of tone of voice etc.) 

verb
  • To utter in a singsong voice. 

noun
  • A drawling or monotonous tone, as of a badly executed song. 

  • Bad singing or poetry. 

  • An informal gathering at which songs are sung; a singing session. 

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

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