pre·fect 
/ˈpri:ˌfɛkt/ noun
plural pre·fects /ˈpri:ˌfɛkt/ noun [count] 1 : a chief officer or government official who is responsible for a particular area in some countries (such as Japan and France) 2 chiefly Brit : an older student who is given the job of helping to watch and control younger students in a school
