HSK 7-9
闷
mēn形动
stuffy; shut indoors; to smother; to cover tightly
屋里太闷，大家打开了窗户。
Wūlǐ tài mēn, dàjiā dǎkāi le chuānghu.
The room was too stuffy, so everyone opened the windows.
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Appears across levels (7-9) in the HSK 3.0 word list.