Main entry: tall, marvellous, marvelous, improbable
Definition: too improbable to admit of belief
Usage: a tall story
Main entry: improbable, unlikely
Definition: not likely to be true or to occur or to have occurred
Usage: legislation on the question is highly unlikely; an improbable event
Main entry: improbable, unbelievable, unconvincing, unlikely
Definition: having a probability too low to inspire belief