a cappella vs medley

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. 

medley

noun
  • A collection of related songs played or mixed together as a single piece. 

  • A collection or mixture of miscellaneous things. 

  • A competitive swimming event that combines the four strokes of butterfly, backstroke, breaststroke, and freestyle. 

  • A cloth of mixed colours. 

verb
  • To combine, to form a medley. 

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