Impossible vs. Improbable

Impossibleadjective

Not possible; not able to be done or happen.

‘It is difficult, if not impossible, to memorize 20,000 consecutive numbers.’; ‘Sarah thinks that nothing is impossible because things can always somehow happen.’;

Improbableadjective

Not likely to be true.

‘It's highly improbable that aliens abducted you.’;

Impossibleadjective

Very difficult to deal with.

‘You never listen to a word I say – you're impossible!’;

Improbableadjective

Not likely to happen.

‘Due to the loss of power, it is improbable that we will begin on time.’;

Impossibleadjective

imaginary

‘impossible quantities, or imaginary numbers’;

Improbableadjective

Not probable; unlikely to be true; not to be expected under the circumstances or in the usual course of events; as, an improbable story or event.

‘He . . . sent to Elutherius, then bishop of Rome, an improbable letter, as some of the contents discover.’;

Impossiblenoun

(obsolete) an impossibility

Improbableadjective

not likely to be true or to occur or to have occurred;

‘legislation on the question is highly unlikely’; ‘an improbable event’;

Impossibleadjective

Not possible; incapable of being done, of existing, etc.; unattainable in the nature of things, or by means at command; insuperably difficult under the circumstances; absurd or impracticable; not feasible.

‘With men this is impossible; but with God all things are possible.’; ‘Without faith it is impossible to please him.’;

Improbableadjective

having a probability to low to inspire belief

Impossiblenoun

An impossibility; as, he tried to do the impossible.

‘"Madam," quoth he, "this were an impossible!"’;

Improbableadjective

too improbable to admit of belief;

‘a tall story’;

Impossiblenoun

something that cannot be done;

‘his assignment verged on the impossible’;

Impossibleadjective

not capable of occurring or being accomplished or dealt with;

‘an impossible dream’; ‘an impossible situation’;

Impossibleadjective

totally unlikely

Impossibleadjective

used of persons or their behavior;

‘impossible behavior’; ‘insufferable insolence’;

Impossibleadjective

not able to occur, exist, or be done

‘it was almost impossible to keep up with him’; ‘a seemingly impossible task’;

Impossibleadjective

very difficult to deal with

‘she was in an impossible situation’;

Impossibleadjective

(of a person) very unreasonable

‘what an arrogant impossible fool’;