vouch vs vow

vouch

noun
  • An assertion, a declaration; also, a formal attestation or warrant of the correctness or truth of something. 

verb
  • To assert, aver, or declare (something). 

  • To provide evidence or proof. 

  • To back, confirm, or support (someone or something) with credible evidence or proof. 

  • To call on (someone) to be a witness to something. 

  • To affirm or warrant the correctness or truth of (something); also, to affirm or warrant (the truth of an assertion or statement). 

  • To bear witness or testify; to guarantee or sponsor. 

  • To cite or rely on (an authority, a written work, etc.) in support of one's actions or opinions. 

  • To bear witness or testify to the nature or qualities (of someone or something). 

  • In full vouch to warrant or vouch to warranty: to summon (someone) into court to establish a warranty of title to land. 

  • Followed by over: of a vouchee (a person summoned to court to establish a warranty of title): to summon (someone) to court in their place. 

  • To express confidence in or take responsibility for (the correctness or truth of) something. 

vow

noun
  • A declaration or assertion. 

  • A solemn promise to perform some act, or behave in a specified manner, especially a promise to live and act in accordance with the rules of a religious order. 

verb
  • To declare publicly that one has made a vow, usually to show one's determination or to announce an act of retaliation. 

  • To make a vow; to promise. 

  • To make a vow regarding (something). 

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