Как по Английски будет impensable

adjective

(of a situation or event) too unlikely or undesirable to be considered a possibility.

Примеры использования:

It was unthinkable that john could be dead

adverb

In a way that is difficult or impossible to think about, often because it is too sad or shocking

Примеры использования:

If we had not taken action, the outlook would have been unthinkably grim., what if, unthinkably, so…