–noun- Slang: a penitentiary (usually prec. by the)

A prison for those convicted of major crimes.

Penitentiary/Adj.1.Of or for the purpose of penance; penitential. 2.Relating to or used for punishment or reform of criminals or wrongdoers

3.Resulting in or punishable by imprisonment in a penitentiary. Ex: a penitentiary offense.