"Reg" is a slang term that can be used to refer to a variety of things, including a person's name, a type of vehicle, or even a regulation or law. When looking for synonyms for "Reg," it's important to consider the context in which it is being used. For example, "Reggie" or "Reginald" could be used as synonyms for the name variation of "Reg." "Regulation" or "ordinance" could be used to describe a type of law or rule. "Ride" or "transportation" could be used to describe a type of vehicle, such as a bike or a car. Overall, the synonyms for "Reg" will depend on the specific usage and context.