a cappella vs lyric

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. 

lyric

noun
  • The words of a song or other vocal music. 

  • A lyric poem. 

adj
  • Of or relating to the lyre (or sometimes the harp) 

  • Of or relating to a writer of such poetry 

  • Having a light singing voice of modest range 

  • Of or relating to musical drama and opera 

  • lyrical 

  • Of, or relating to a type of poetry (such as a sonnet or ode) that expresses subjective thoughts and feelings, often in a songlike style 

  • melodious 

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