阻塞 (zǔsè) is a compound word formed from 阻 (zǔ), meaning 'to obstruct' or 'to hinder', and 塞 (sè), meaning 'to block' or 'to stuff'. Together, they emphasize complete or severe obstruction — not just a partial slowdown, but a full stoppage of flow. It commonly describes physical blockages in biological, mechanical, or systemic contexts: blood vessels, pipes, traffic, data networks, or even abstract channels like communication.

The word carries a slightly formal or technical tone and appears frequently in medical, engineering, and bureaucratic language. As a verb, it takes objects directly (e.g., 阻塞血管); as a noun, it often follows classifiers like 一處 (yì chù) or 一種 (yì zhǒng). Unlike the more casual 堵 (dǔ), 阻塞 implies seriousness and often urgency — for example, a blocked artery or a clogged sewer line demands immediate attention.