UNTHINKABLE

[adjective] - too shocking or unlikely to be imagined as possibleFor most people in this country, the prospect of war is unthinkable.You can't imagine what it would be like to have your child die - it's quite unthinkable.Nowadays wines are being produced in areas that would have been unthinkable even ten years ago.The unthinkable had happened - his secret activities had been discovered by the press.