The word 代号 is formed by combining two characters whose core concepts merge to create a new, unified meaning. The first character, 代 (dài), carries the fundamental idea of "substituting for" or "acting on behalf of" something else. The second character, 号 (hào), holds the essential concept of a "name", "label", or "designation". When fused, the compound naturally conveys the idea of a "substitute name", a designated label that stands in for and represents something else, such as a person, object, or operation, typically for the purposes of secrecy, brevity, or standardization.