cassock vs ecclesiast

cassock

noun
  • An item of clerical clothing: a long, sheath-like, close-fitting, ankle-length robe worn by clergy members of some Christian denominations. 

ecclesiast

noun
  • A cleric; someone (such as a priest) who administers a church (ecclesia) or other religious gathering/group. 

  • A member of the Athenian ecclesia (public legislative assembly). 

  • A member of any ecclesia (church or other assembly). 

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