missive vs monitory

missive

noun
  • A written message; a letter, note or memo. 

  • Letters sent between two parties in which one makes an offer and the other accepts it. 

adj
  • Specially sent; intended or prepared to be sent. 

monitory

noun
  • a written letter giving admonition 

adj
  • giving admonition and warning 

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