堵 On the HSK 4 vocabulary list, at CEFR level B2. dǔ ㄉㄨˇ to block up (a road, pipe etc) to stop up (a hole) (of a person) choked up with anxiety or stress fig. wall (literary) (classifier for walls) Sources CC-CEDICT, CC BY-SA 4.0 pinyinjs, Apache-2.0 国际中文教育中文水平等级标准, 中华人民共和国教育部, MIT