a cappella vs words

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. 

words

noun
  • Lyrics. 

  • Angry debate or conversation; argument. 

  • Lines in a script for a performance. 

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