Praepostor (sometimes speltPraepositor) is a term now used chiefly atEnglishindependent schools, such asAldenham,Brentwood,Clifton,Eton,Giggleswick,Harrow,Rugby,Shrewsbury,Tonbridge andUppingham as well as at other schools such as the formerDerby School which began asgrammar schools for the teaching ofLatin grammar. It is the equivalent ofprefect. The word originally referred to a monasticprior and is lateLatin of theMiddle Ages, derived from classical Latinpraepositus, "placed before".
The use ofpraepostor in the context of a school is derived from the practice of using older children to lead or control younger children. This originally involved both leading in lessons and keeping general discipline, but latterly it involved only discipline.
Children helping to lead classes were also calledmonitors, and the termspraepostor andmonitor are roughly equivalent toprefect andsub-prefect in many other English schools.