The phrase "rather impossible" is correct and usable in written English.
You can use it to indicate something that is very difficult, or approaching the impossible. For example, "Getting to the summit of the mountain in a day was rather impossible."
Once the idea was suggested, it seemed rather impossible not to do it.
I find that rather impossible to believe considering that I have only followed four people.
Likewise, impressionistic stock footage that accompanies recollections of Malala's stay in hospital feels only a couple of steps up from ER. Malala herself is impossible to question; or, rather, impossible to unsettle.
If you're looking for a hotel bar plunked down in the midst of a bustling, hip neighborhood, it is really rather impossible to beat Hotel on Rivington's Thor, a lounge (and in the back, a restaurant) on a particularly happening stretch of Rivington Street in the 21st-century playground known as the Lower East Side.
Three examples show why in the sequence case so direct formula is rather impossible.
I guess it was always inevitable, but it seemed rather impossible at the time.
I appreciated the word "complicated," rather than "impossible".
Rather, The Impossible Exile braids this hugely successful writer's ordeal of dispossession and homelessness after 1934 with the trajectory of Prochnik's own family – like Zweig's, Viennese Jews who moved to the Americas.
It is not so much that gender is performed in front of us; rather, the impossible quest to live up to normative standards is physicalised, and if it does not quite work as metaphor, it certainly works as a showcase of endurance.
Violations were improbable rather than impossible.
Perpetual motion machines of the second kind become improbable rather than impossible.
