季伯 (jì bó) is a traditional Chinese kinship term meaning 'fourth uncle'—specifically, the fourth-oldest paternal uncle (father’s brother) in a family. The character 季 (jì) originally denotes the last of a sequence (e.g., the fourth season, winter), and in kinship terms signals the youngest or last-born among siblings; 伯 (bó) refers to the eldest brother of one’s father. Together, 季伯 identifies the father’s youngest brother, following the classical birth-order naming system where 伯 (eldest), 仲 (second), 叔 (third), and 季 (fourth) mark paternal uncles’ relative seniority.

This term reflects Confucian-influenced family hierarchy and is still used in formal contexts, ancestral rituals, or respectful address—especially in rural areas or among older generations. It is not commonly used in casual modern speech, where generic terms like 叔叔 (shūshu) prevail. 季伯 carries connotations of respect and lineage, and may appear in written family histories, genealogies, or ceremonial introductions.