(1):
(n.) A dignitary or presiding officer in certain ecclesiastical and lay bodies; esp., an ecclesiastical dignitary, subordinate to a bishop.
(2):
(n.) The collegiate officer in the universities of Oxford and Cambridge, England, who, besides other duties, has regard to the moral condition of the college.
(3):
(n.) The head or presiding officer in the faculty of some colleges or universities.
(4):
(n.) A registrar or secretary of the faculty in a department of a college, as in a medical, or theological, or scientific department.
(5):
(n.) The chief or senior of a company on occasion of ceremony; as, the dean of the diplomatic corps; - so called by courtesy.