Correctional describes things related to prisons and the system that supervises people who have broken the law. A correctional facility is the formal term for a jail or prison. Correctional officers are the people who work in these facilities, maintaining order and safety.

You might read about the correctional system in a news article or history book. This refers to the entire network of prisons, jails, and programs designed to punish crimes and, ideally, prevent people from committing them again. Some places also have correctional education programs that teach job skills to people in prison, or correctional counselors who try to help people address problems that led them to break the law.

The word sounds more official and less harsh than “prison,” which is partly why government agencies and news organizations use it. When you hear someone works in corrections, it means they're part of this system in some way.