avow vs fess

avow

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

  • To bind or devote by a vow. 

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

fess

verb
  • To confess; to admit. 

noun
  • A horizontal band across the middle of the shield. 

adj
  • Of animals, bad-tempered, fierce. 

  • Lively; active; strong. 

  • Proud; conceited. 

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