Merriam-Webster Collegiate Dictionary - penitentiary

 I. noun  (plural -ries)  Etymology: Middle English penitenciary, from Medieval Latin poenitentiarius, from poenitentia  Date: 15th century  1.  a. an officer in some Roman Catholic dioceses vested with power from the bishop to deal with cases of a nature normally handled only by the bishop  b. capitalized a cardinal presiding over a tribunal of the Roman curia concerned with dispensations and indulgences  2. a public institution in which offenders against the law are confined for detention or punishment; specifically a state or federal prison in the United States  II. adjective  Date: 1577  1. penitential  2. of, relating to, or incurring confinement in a ~