Education. the head of a faculty, school, or administrative division in a university or college: the dean of admissions. an official in an American college or secondary school having charge of student personnel services, such as counseling or discipline: the dean of men. the official in charge of undergraduate students at an English university.
Ecclesiastical. the head of the chapter of a cathedral or a collegiate church. Also called vicar forane. a priest in the Roman Catholic Church appointed by a bishop to take care of the affairs of a division of a diocese.
the senior member, in length of service, of any group, organization, profession, etc.: the dean of lexicographers.