ex cathedra vs unofficial

ex cathedra

prep
  • With authority based on one's rank or office. 

unofficial

adj
  • Not officially established. 

  • Not acting with official authority. 

  • Implicitly true but withheld and/or contradicted by authority. 

  • Not listed in a national pharmacopeia etc. 

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