commissioner       
noun [ C ] uk/kəˈmɪʃ.ən.ər/ us/kəˈmɪʃ.ən.ɚ/
 (政府部门或某一组织的)委员,专员,特派员,长官
an important official who has responsibility in a government department or another organization
  the commissioner in charge of the police force 负责伦敦警察队伍的长官