The term ONE ACTING ON BEHALF OF ANOTHER can be summarized as an AGENT, which is a 5 letter word. An AGENT is someone who acts on behalf of another person or organization. Agents are often used in business and legal contexts to represent the interests of their clients. They may negotiate contracts, manage investments, or provide advice on legal matters. Agents can also be used in entertainment, such as when actors hire agents to represent them in negotiations with studios.