'直属系' literally combines '直' (direct), '属' (to belong to), and '系' (department or division). Together, it denotes a department that reports directly to a higher-level authority—bypassing intermediate administrative levels. It emphasizes formal organizational hierarchy, commonly used in universities, government agencies, and large enterprises where structural clarity matters.

This term appears in official documents, organizational charts, and administrative announcements. Unlike general terms like '部门' (department), '直属系' signals specific chain-of-command relationships: for example, a university's '教务处直属系' means the Academic Affairs Office’s directly managed units. It is not used for informal or functional groupings, nor for family or social ties—it is strictly institutional and bureaucratic.