a cappella vs glee

a cappella

noun
  • A vocal performance with no 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. 

adj
  • Singing solely or mainly without instrumental accompaniment. 

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

glee

noun
  • An unaccompanied part song for three or more solo voices, not necessarily merry. 

  • Music; minstrelsy; entertainment. 

  • Joy; happiness; great delight, especially from one's own good fortune or from another's misfortune. 

verb
  • To sing a glee (unaccompanied part song). 

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