A plug valve is a type of valve that uses a cylindrical or conical plug to control the flow of fluid through the valve. While "plug valve" is the most commonly used term, there are several synonyms that can be used to describe this type of valve. One synonym is "cock valve", which is a more informal term used to describe valves that are used in household plumbing. Other synonyms for plug valve include "rotary valve" and "stop-cock valve". Regardless of the term used, plug valves are known for their simplicity, reliability, and ease of maintenance, making them a popular choice for a wide range of applications in the oil and gas, chemical, and water treatment industries.