declare vs vow

declare

verb
  • To assert or announce formally, officially, explicitly, or emphatically. 

  • To make outstanding debts, e.g. taxes, payable. 

  • To show one's cards in order to score. 

  • To explicitly establish the existence of (a variable, function, etc.) without necessarily describing its content. 

  • For a constituency in an election to officially announce the result 

  • For the captain of the batting side to announce the innings complete even though all batsmen have not been dismissed. 

  • To inform government customs or taxation officials of goods one is importing or of income, expenses, or other circumstances affecting one's taxes. 

vow

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). 

noun
  • 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. 

  • A declaration or assertion. 

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