制约 (zhìyuē) is a verb meaning 'to restrict', 'to constrain', or 'to check' — especially in formal, systemic, or institutional contexts. The character 制 (zhì) means 'to control' or 'to regulate', while 约 (yuē) means 'to bind', 'to limit', or 'to agree upon'. Together, they convey the idea of mutual or structural limitation — not just arbitrary restriction, but a built-in, often reciprocal, limiting force. It's frequently used in political science (e.g., checks and balances), economics (market constraints), medicine (biological limits), and environmental science (ecological carrying capacity).

This word implies an objective, often impersonal, limiting factor — something that cannot be easily overridden. It’s more formal and abstract than common synonyms like 限制 (xiànzhì) and carries a sense of systemic interdependence: one thing制约s another not out of will, but due to inherent conditions or rules.