The word 外婆 is formed by combining two characters: 外, meaning "outside" or "external", and 婆, meaning "elderly woman" or "grandmother". This construction reflects the traditional Chinese kinship system where familial relations are categorized by paternal (內, inside) and maternal (外, outside) lines. Therefore, 外婆 specifically denotes the maternal grandmother, the grandmother from the "outside" or external branch of the family, visually and conceptually distinguishing her from the paternal grandmother (奶奶).