Prison planet

A prison planet is any planet where the entire world is dedicated to the incarceration of criminals. Under the rule of House Corrino, the Imperial Prison Planet was designated Salusa Secundus after the removal of the royal court to Kaitain.

During the rule of House Corrino nobles and loyalists of disgraced houses were exiled en masse to Tupile, a mysterious prison planet which may in fact have been a collection of such worlds.

Dune Encyclopedia
The Dune Encyclopedia mentions a Prison Planet named Liesco II.