acquittance vs unbinding

acquittance

noun
  • The release from a debt, or from some obligation or duty; exemption. 

  • A writing which is evidence of a discharge; a receipt in full, which bars a further demand. 

unbinding

noun
  • The release or freeing of something that was bound. 

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