The word 兄弟 is formed by combining two pictographic characters, each representing a distinct familial role, to create a unified concept. The character 兄 depicts an older brother, originally showing a figure with an open mouth, suggesting one who speaks with authority or instructs. The character 弟 represents a younger brother, derived from an ancient pictogram of a sequence of bindings on an arrow shaft, implying order and succession. When placed together, they visually and conceptually merge the specific ideas of "elder" and "younger" into the broader, collective meaning of "brothers" or brotherhood.