a cappella vs isolate

a cappella

noun
  • A vocal performance with no instrumental accompaniment. 

adj
  • Singing solely or mainly without instrumental accompaniment. 

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

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. 

isolate

noun
  • Something that has been isolated. 

verb
  • To self-isolate. 

  • To separate a pure strain of bacteria etc. from a mixed culture. 

  • To separate a substance in pure form from a mixture. 

  • To insulate, or make free of external influence. 

  • To insulate an electrical component from a source of electricity. 

  • To set apart or cut off from others. 

  • To place in quarantine or isolation. 

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