improbable

Unlikely to take place or be true.

Not probable; not likely to be true; not to be expected under the circumstances of the case.

Not probable; unlikely to be true; not to be expected under the circumstances or in the usual course of events.

Not likely to be true.

Not likely to happen.

having a probability too low to inspire belief

too improbable to admit of belief

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