Penitentiary (noun)

1. A prison for individuals serving long-term sentences.
2. An institution for the confinement of convicted criminals and the rehabilitation of offenders through a system of penal labor and reeducation.

Origin:

From latin poenitentiarius, from poenitens ("penitent") + -arius.

Examples:

1. He was sentenced to life in a penitentiary.
2. The penitentiary was overcrowded and unsanitary.
3. The penitentiary system aimed to reform rather than simply punish criminals.
4. The penitentiary was a formidable and imposing structure.
5. He served his time in the penitentiary and was released on parole.