Incredible means “hard to believe, unbelievable”: His explanation of the cause of the accident was simply incredible. It is often used more loosely to mean “astonishing,” as in The new pitcher has an incredible fastball. Incredulous usually means “skeptical, disbelieving,” as in The incredulous reporters laughed at the manager’s explanation of how the funds disappeared. It is sometimes extended to mean “showing disbelief,” as in an incredulous stare. You may occasionally see incredulous used where you would expect incredible, as in an incredulous display of rudeness. This usage is not well established, however, and is widely considered an error.
