mouth off vs pronounce

mouth off

verb
  • To complain or otherwise express oneself in a loud, immoderate manner. 

  • To talk impudently, especially to one's superior. 

pronounce

verb
  • To sound out (a word or phrase); to articulate. 

  • To pronounce dead. 

  • To declare formally, officially or ceremoniously. 

  • To pass judgment. 

  • To sound like. 

  • To produce the components of speech. 

  • To declare authoritatively, or as a formal expert opinion. 

  • To read aloud. 

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