| sì | four/4 |
| 四 | four 4 |
| 四一二 | 12th April refers to Chiang Kai-shek's coup of 12th April 1927 against the communists in Shanghai |
| 四一二事变 | the coup of 12th Mar 1927, an attempt by Chiang Kai-shek to suppress the communists called 反革命政变|反革命政變 or 慘案|惨案 in PRC literature |
| 四一二反革命政变 | counterrevolutionary coup of 12th April 1927, Chiang Kai-shek's coup against the communists in Shanghai |
| 四一二惨案 | the massacre of 12th Mar 1927 the Shanghai coup of 12th Mar 1927 by Chiang Kai-shek against the communists |
| 四下 | everywhere |
| 四下环顾 | to look about |
| 四下里 | all around |
| 四不像 | milu |
| 四世同堂 | Four Generations under One Roof, novel by Lao She 老舍 |
| 四个一组的 | quaternate; quarternate |
| 四个现代化 | Deng Xiaoping's four modernizations practiced from the 1980s (possibly planned together with Zhou Enlai), namely: modernization of industry, agriculture, national defense and science and technology abbr. to 四化 |
| 四乙基铅中毒 | tetraethyl lead poisoning |
| 四乙铅 | tetraethyl lead; tetraethyllead; Tetra-ethyl lead; ethyl |
| 四乡 | countryside around a town |
| 四书 | Four Books, namely: the Great Learning 大學|大学, the Doctrine of the Mean 中庸, the Analects of Confucius 論語|论语, and Mencius 孟子 |
| 四书五经 | Four Books and the Five Classics |
| 四人帮 | Gang of Four: Jiang Qing 江青, Zhang Chunqiao 張春橋, Yao Wenyuan 姚文元, Wang Hongwen 王洪文, who served as scapegoats for the excesses of the cultural revolution |
| 四价 | [Chemistry] quadrivalence |
| 四价元素 | [Chemistry] tetrad |