hierarch vs metropolitan

hierarch

noun
  • A title of bishops in their role as ordinaries (arbiters of canon law) over their respective dioceses. 

  • One who has high and controlling authority in sacred things; the chief of a sacred order. 

metropolitan

noun
  • A bishop empowered to oversee other bishops; an archbishop. 

  • The inhabitant of a metropolis. 

adj
  • Of or pertaining to the parent state of a colony or territory, or the home country, e.g. metropolitan France 

  • Pertaining to the see or province of a metropolitan. 

  • Of, or pertaining to, a metropolis or other large urban settlement. 

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