Definition:
incredulous is the adjective that can be used to describe a person who expresses incredulity at something they are hearing.
Examples:
He was an incredulous listener, unable to believe the news.
The incredulous, disbelieving look on her face was clear to all present.
Tips:
the adjective form of incredulousness is not usually used as a positive feeling, as its often rooted in disbelief; instead, its usually used to express an extreme negative reaction.