proconsul vs warden

proconsul

noun
  • A magistrate who served as a consul and then as the governor of a province. 

warden

noun
  • A governing official in various institutions 

  • An official charged with supervisory duties or with the enforcement of specific laws or regulations; such as a game warden or air-raid warden 

  • A variety of pear. 

  • A chief administrative officer of a prison. 

verb
  • To carry out the duties of a warden. 

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