ballad vs motet

ballad

noun
  • A kind of narrative poem, adapted for recitation or singing; especially, a sentimental or romantic poem in short stanzas. 

  • A slow romantic song. 

verb
  • To compose or sing ballads. 

motet

noun
  • A composition adapted to sacred words in the elaborate polyphonic church style; an anthem. 

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