Learner's definition of IMPOSSIBLE
unable to be done or to happen
It's impossible to predict the future.
The heavy rain made it impossible to see the road.
It's logically/mathematically impossible.
It's physically impossible for a child to lift that much at once.
It's virtually/nearly/almost impossible to book a flight just before the holiday.
I find it impossible to believe [=I cannot believe] that he's telling the truth.
an impossible dream
[more impossible; most impossible]
of a person
very difficult to deal with
very irritating or annoying
something that cannot be done or that is very difficult
The restaurants in this city are impossibly [=extremely, ridiculously] expensive.
impossibly high standards