witches' stone

Meanings

1. A small ledge jutting out of the chimney of a house, chiefly in Jersey or Guernsey, originally to stop rain seeping under the joins in a thatched roof, and later reinterpreted in folklore as a place for witches to rest.
2. An adder stone, a stone with a (natural) hole in it.
3. Used other than figuratively or idiomatically: see witch, stone.