The word 侄女 is formed by combining two meaningful components: 侄, which originally and specifically means "brother's son" (nephew), and 女, meaning "female". By adding 女 to 侄, the term shifts the reference from a male nephew to specifically a "brother's daughter", creating a single, clear concept for a niece (in the paternal line). It is a direct and logical construction where the gender modifier follows the core familial role.