Definition of "gaol"

‘[…] There's every Staffordshire crime-piece ever made in this cabinet, and that's unique. The Van Hoyer Museum in New York hasn't that very rare second version of Maria Marten's Red Barn over there, nor the little Frederick George Manning—he was the criminal Dickens saw hanged on the roof of the gaol in Horsemonger Lane, by the way—’

1963, Margery Allingham, chapter 3, in The China Governess‎

Sirius had been in Azkaban, the terrifying wizard gaol guarded by creatures called Dementors

2000, J. K. Rowling, Harry Potter and the Goblet of Fire, Bloomsbury Publishing, page 26