The Chinese word for uncle is
叔叔

shū shū

Chinese Definition

uncle
1. 泛指高自己一輩的男性親人，或父母的男性好友，又或對普通年長男性的親暱稱謂
2. 伯父
3. 叔父
4. 姑父
5. 姨丈
6. 舅父
7. 老伯伯
8. 当铺
9. 大爷
Components
叔
1. paternal uncle (father's younger brother)
2. brother-in-law (husband's younger brother)
3. uncle (a term of address for a man around one's father's age or slightly younger)
4. (historical) shu, (ngd, a high rank in the early Zhou aristocracy)
(ux, zh, 三監是管叔鮮、蔡叔度和霍叔處。, The Three Guards were Guanshu Xian, Caishu Du, and Huoshu Chu.)
5. (obsolete) to gather; to harvest
叔
1. paternal uncle (father's younger brother)
2. brother-in-law (husband's younger brother)
3. uncle (a term of address for a man around one's father's age or slightly younger)
4. (historical) shu, (ngd, a high rank in the early Zhou aristocracy)
(ux, zh, 三監是管叔鮮、蔡叔度和霍叔處。, The Three Guards were Guanshu Xian, Caishu Du, and Huoshu Chu.)
5. (obsolete) to gather; to harvest

叔叔
1. n. paternal uncle (father's younger brother)
2. n. (often, childish) uncle (term of address for a man around one's father's age or slightly younger)

伯父
1. n. (formal) paternal uncle (father's elder brother)
2. n. (formal) uncle (a term of respect for someone who is slightly older than one's father)
3. n. (Cantonese) old man, especially one who is creepy

伯伯
1. n. (informal, affectionate) paternal uncle (father's elder brother)
2. n. (informal, affectionate) uncle (a term of respect for someone who is older than one's father)
3. n. (dialectal) father
4. n. (dialectal) paternal aunt (father's sister, or wife of father's elder brother)
5. n. (Suzhou Wu) brother-in-law (husband's elder brother)

叔父
1. n. (formal) paternal uncle (father's younger brother)
2. n. (Cantonese) elder in a gang; someone who is of the same generation as the gang leader