a cappella vs isolated

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. 

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. 

isolated

adj
  • Placed or standing apart or alone; in isolation. 

  • Affecting 10 percent to 20 percent of a forecast zone. 

  • Happening or occurring only once. 

  • Such that no pawn of the same color is in an adjacent file. 

  • Which has been extracted from the organism. 

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