Refusing or reluctant to believe
I was incredulous when he first told me the secret.
He was at first incredulous, but eventually learned the truth.
I'm still incredulous at the idea that oil had nothing to do with this political problem in the Middle East.
He was incredulous as a Missouri cynic but interested.
When she opened them, incredulous that Jackson had gotten away with his joke, he grinned innocently and shrugged.