- 1: the head of the chapter of a collegiate or cathedral church
- 2: a person who is in charge of one of the parts of a university (such as a college or school)
- 3: a person whose job is to give advice to the students in a college or high school and to make sure that they obey the school's rules
- 4: a person who has more experience in or knowledge about a particular profession, subject, etc., than anyone or almost anyone
In academic administrations such as school or colleges, a dean is the person with significant authority over a specific academic unit, or over a specific area of concern, or both. Deans are occasionally found in middle schools and high schools as well.
The term comes from the Latin decanus, "a leader of ten", taken from the medieval monasteries (particularly those following the Cluniac Reforms) which were often extremely large, with hundreds of monks (the size of a small college campus). The monks were organized into groups of ten for administrative purposes, along the lines of military platoons, headed by a senior monk, the decanus. The term was later used to denote the head of a community of priests, as the chapter of a cathedral, or a section of a diocese (a "deanery"). When universities grew out of the cathedral and monastery schools, the title of dean was used for officials with various administrative duties.