拥塞 (yōngsè) is a verb meaning 'to be congested' or 'to clog', describing a state where movement or flow is severely hindered due to excessive density or accumulation. The first character 拥 (yōng) means 'to crowd' or 'to gather densely', often implying pressure from many entities in close proximity; the second character 塞 (sè) means 'to block' or 'to obstruct', suggesting physical or functional impaction. Together, they vividly convey a situation where space, passage, or capacity is overwhelmed — most commonly used for traffic, networks, or crowded public areas.

This word is typically used in formal or descriptive contexts — you’ll see it in news reports, urban planning discussions, and health advisories about emergency rooms. It’s rarely used for abstract concepts like emotions or thoughts, and almost never for living beings themselves (e.g., you wouldn’t say 'the crowd is 拥塞'; instead, you’d say 'the street is 拥塞'). It functions as a stative verb and often appears with degree adverbs like 严重 (severely) or 高度 (highly), or in passive-like constructions such as 被拥塞 (became congested).