nie do pomyślenia Anglais:

I was unthinkable that John could be dead

To us this seems unthinkable

something unthinkable even a generation ago

An agreement between the two countries was unthinkable.

The idea of late trains is almost unthinkable.

do pomyślenia How would you cope if the unthinkable happened?

The even greener alternative to recycling seems almost unthinkable: it’s to keep your current phone for more than the usual 12 months!

It is practically unthinkable that a scientist of his stature would have made such an elementary mistake.

Essentially it's a one-to-one match, but the content of that match is a level so high as to be unthinkable to an ordinary person.