The word "保镖" is formed by combining two characters: "保", which means to protect or guard, and "镖", which originally referred to a dart or a throwing weapon used by armed escorts in ancient China. Together, they create a conceptual compound where the first character denotes the action ("to protect") and the second character denotes the instrumental object ("dart/weapon"), metaphorically representing the person, the professional bodyguard or security guard, who provides protection, much like the armed escorts of the past.