hierarch vs reverend

hierarch

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

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

reverend

noun
  • A member of the Christian clergy; a minister. 

adj
  • worthy of reverence or respect 

  • reverent 

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