purgatory (n.) Look up purgatory at Dictionary.com
c.1200, from Old French purgatore and directly from Medieval Latin purgatorium (St. Bernard, early 12c.), in Latin, "means of cleansing," noun use of neuter of purgatorius (adj.) "purging, cleansing," from purgat-, past participle stem of Latin purgare (see purge (v.)). Figurative use from late 14c.