Penitentiary is a term that refers to a type of prison that is meant for long-term incarceration for serious crimes. Some of the synonyms for penitentiary include correctional facility, maximum security prison, prison or jail. Other synonyms for the word include detainment center, lockup, correctional institution and penal colony. These words are often used interchangeably to describe facilities that are meant to hold criminals, and they share common characteristics such as being highly secure, having a regimented routine and being designed to keep inmates away from society. However, each word can have its nuances and may be affected by the laws and regulations of different regions and countries.