A membrane covering (anatomy).
Therefore I will be unto them as a lion: as a leopard by the way will I observe them: I will meet them as a bear that is bereaved of her whelps, and will rend the CAUL of their heart, and there will I devour them like a lion: the wild beast shall tear them. ( Hosea 13:7-8 )
Bibliography Information"Entry for 'Caul'". A King James Dictionary.