ipse dixit vs pronouncement

ipse dixit

noun
  • An authority who makes such an assertion. 

  • A dogmatic and unproved proposition or dictum that is accepted solely on the authority of someone who is known to have asserted it. 

pronouncement

noun
  • An utterance. 

  • An official public announcement. 

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