Wiktionary
unattainably
adv. In an unattainable way.
WordNet
unattainably
adv. in an unattainable manner or to an unattainable degree; "this house is unattainably expensive" [syn: unachievably]
Usage examples of "unattainably".
The darkness ahead will be tricky to negotiate, and the simple trials of what he’s already starting to characterize as his old life seem, despite blood and attrition, unattainably desirable.
As for the Andromeda Galaxy, humanity's closest neighbor, it remained unattainably distant.
Suddenly, Aydrian’s corporeal form seemed so much farther away, almost unattainably so!
I had abandoned that wish as a part (I thought) of growing up, when I learned that only people whose positions in society appeared to me unattainably high ever succeeded in leaving Urth.