‘同姓’ literally means ‘same surname’—‘同’ (tóng) means ‘same’ or ‘identical’, and ‘姓’ (xìng) means ‘surname’ or ‘family name’. Together, they form a noun describing the condition of two or more people sharing the same family name. This term is commonly used in social, historical, and genealogical contexts—for example, when discussing clan relationships, marriage customs (where traditional taboos sometimes discouraged marriage between people with the same surname), or identity verification in official settings.

In modern usage, ‘同姓’ appears in formal writing, academic discussions about kinship, and everyday conversations about personal background—e.g., discovering a colleague shares your surname and remarking, ‘我们是同姓！’ (‘We have the same surname!’). It’s neutral in register but carries subtle cultural weight, reflecting China’s long-standing emphasis on lineage and ancestral ties.