impossible

As adjectives the difference between impossible and difficult

is that impossible is not possible; not able to be done or happen while difficult is hard, not easy, requiring much effort.

As a noun impossible

is {{cx|obsolete|lang=en}} an impossibility.

As a verb difficult is

to make difficult; to impede; to perplex.

As adjectives the difference between impossible and unimpossible

is that impossible is not possible; not able to be done or happen while unimpossible is not impossible: possible.

As a noun impossible

is {{cx|obsolete|lang=en}} an impossibility.

As nouns the difference between impossible and hypercomputation

is that impossible is an impossibility while hypercomputation is (computing) any of several forms of computation that are theoretically (or practically) impossible with current technology.

As an adjective impossible

is not possible; not able to be done or happen.