Final answer:
A special agent is empowered to act on behalf of a person or firm for a specific event or transaction.
Step-by-step explanation:
An agent who is empowered to act on behalf of a person or firm for one specific event or transaction is a special agent. Special agents are appointed for a particular purpose or task and have limited authority. Unlike general agents who have broader authority and can act on behalf of a principal in a wide range of matters.