monitor [monitors](someone who watches over something) noun [UK: ˈmɒ.nɪ.tə(r)] [US: ˈmɑː.nə.tər]
supervisor [supervisors](a person with the official task of overseeing the work of a person or group etc.) noun [UK: ˈsuː.pə.vaɪ.zə(r)] [US: ˈsuː.pər.ˌvaɪ.zər]