‘Gūgu’ is a kinship term referring specifically to one’s father’s sister — that is, a paternal aunt. The repetition of the character 姑 (gū) adds warmth and familiarity, making it an affectionate, informal form used especially by children or within close family settings. While 姑 alone can mean ‘aunt’ or ‘unmarried woman’ in classical or formal contexts, doubling it creates a tender, diminutive nuance — similar to saying ‘Auntie’ instead of ‘Aunt’ in English.

This term carries no implication about marital status (unlike ‘gūniang’, which means ‘unmarried girl’) and is never used for maternal aunts — those are called ‘yíyí’. ‘Gūgu’ reflects traditional Chinese emphasis on distinguishing paternal and maternal lineages, and its usage signals closeness, respect, and familial intimacy. It’s common in everyday speech, storytelling, and family-oriented media, but rarely appears in formal documents or professional contexts.