1) Prepositor 
Praepostor (sometimes spelt Praepositor) is now used chiefly at English independent schools, such as Aldenham, Rugby, Giggleswick and Eton at other schools such as the former Derby School which began as grammar schools for the teaching of Latin grammar. It is the equivalent of prefect. The word originally referred to a monastic prior and is late L...
prefect of a school
a senior student at an English public school who is given authority over other students.