堵住 (dǔ zhù) is a compound verb meaning 'to block up' or 'to seal off' — literally, 堵 (dǔ) means 'to block' or 'to obstruct', and 住 (zhù) is a resultative complement indicating that the action has achieved completion or caused something to remain in a fixed state. Together, they convey the idea of successfully stopping flow, passage, or movement — whether physical (like water, air, or traffic) or metaphorical (like emotions or communication).

This verb is commonly used in contexts involving obstruction of bodily functions (e.g., nasal congestion), plumbing issues, road closures, or even emotional suppression. It often appears with objects like 鼻子 (nose), 下水道 (sewer pipe), or 路 (road), and frequently follows subject + verb + object structure: e.g., ‘痰堵住了气管’ (Phlegm blocked the trachea). It implies full, effective blockage — not just partial hindrance.