Buildings or other facilities to which people are legally committed as punishment for a crime or while awaiting trial. In North America, the term specifically denotes a facility run by the state or federal government for those who have been convicted of serious crimes, in contrast to a locally run facility for those awaiting trial or convicted of minor offences. As developed since the late 18th century, prisons are generally characterized by cell and corridor plans with separation by offense and sex, and programs of rehabilitation provided as means toward prisoner reform. Use "jails (buildings)" for places for offenders sentenced either for lesser crimes or relatively short terms.

Source: AAT

http://vocab.getty.edu/page/aat/300006460