closing form vs valediction

closing form

noun
  • A standard formula to end a letter. 

  • A standard formula to end a speech. 

  • A form used to document an important legal transaction. 

  • A form in an authority filled to formally document the closing a case. 

  • A method to end an implemented functionality. 

valediction

noun
  • A word or phrase used to end a letter or message. 

  • A word or phrase (such as adieu or farewell) said upon leaving. 

  • A speech made when leaving or parting company. 

  • The act of parting company. 

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