Definition of St Patrick's Purgatory in English:

St Patrick's Purgatory

(also Purgatory of St Patrick)

noun

  • (The name of) a cavern on an island in Lough Derg, Co. Donegal, Ireland, where according to legend Christ appeared to St Patrick, and showed him a deep pit in which whoever spent one day and one night could behold the torments of hell and the joys of heaven.

Origin

Middle English.