堵塞 (dǔ sè) is a compound word meaning 'blockage' or 'obstruction'. The first character 堵 (dǔ) means 'to stop up' or 'to block', often used for physical barriers like traffic or pipes; the second character 塞 (sè) means 'to stuff' or 'to clog', emphasizing the state of being tightly filled or impeded. Together, they form a versatile term used both as a noun ('a blockage') and a verb ('to obstruct').

This word commonly appears in medical, technical, and everyday contexts — for example, describing nasal congestion, traffic jams, or clogged drains. It carries a neutral-to-negative connotation, implying something is hindering normal flow. While 堵塞 can refer to literal physical obstructions, it’s also used metaphorically, such as in bureaucratic or communication bottlenecks. It’s more formal than colloquial alternatives like 堵 (dǔ) alone, and is frequently paired with words like 造成 (to cause), 发生 (to occur), or 解除 (to remove).