astringe vs avow

astringe

verb
  • To bind by moral or legal obligation. 

avow

verb
  • To bind or devote by a vow. 

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

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

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