Final answer:
Class of service (CoS) is the security service in an enterprise wireless gateway that allows the administrator to assign levels of service to a particular user.
Step-by-step explanation:
The security service in an enterprise wireless gateway that enables the wireless network administrator to assign levels of service to a particular user is called class of service (CoS). CoS is a mechanism used to prioritize user traffic based on predefined policies or rules. It allows the administrator to allocate bandwidth and set priorities for different types of traffic, ensuring that certain users or applications receive better service quality.