制度 (zhì dù) refers to an organized, formal system of rules, laws, or established practices that govern behavior, operations, or relationships within a society, organization, or institution. The character 制 (zhì) means 'to establish', 'to regulate', or 'to control', while 度 (dù) here carries the sense of 'measure', 'standard', or 'norm'—not its more common meaning of 'degree' or 'duration'. Together, they convey the idea of codified standards that shape how things function.

This word is commonly used in political, social, educational, and workplace contexts—for example, describing China’s socialist system (社会主义制度), school disciplinary policies (校规制度), or corporate management structures (管理制度). It implies stability, authority, and long-term structure, distinguishing it from informal customs or temporary arrangements. Unlike the English word 'system', 制度 almost always carries institutional weight and official sanction, not just any organized arrangement.