a cappella vs popular

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. 

popular

noun
  • A person who is popular, especially at a school. 

  • An inexpensive newspaper with wide circulation. 

  • A member of the Populares 

adj
  • Liked by many people; generally pleasing, widely admired. 

  • Common among the general public; generally accepted. 

  • Pertaining to or deriving from the people or general public. 

  • Adapted to the means of the common people; cheap. 

  • Concerning the people; public. 

  • Aimed at ordinary people, as opposed to specialists etc.; intended for general consumption. 

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