avow vs cast off

avow

verb
  • To acknowledge and justify, as an act done. See avowry. 

  • To declare openly and boldly, as something believed to be right; to own, acknowledge or confess frankly. 

  • To bind or devote by a vow. 

cast off

verb
  • To discard or reject something. 

  • To let go (a cable or rope securing a vessel to a buoy, wharf, etc.) so that the vessel may make way. 

  • To finish the last row of knitted stitches and remove them securely from the needle. 

  • To estimate the amount of space required by the type used for the given copy. 

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