If you do something incredulously, you're doing it in a doubting or disbelieving way. If you look at someone incredulously, you can't believe what they're saying or doing.

Incredulously is a word that has to do with disbelief — it's a way of looking at someone or talking to someone like you just can't believe what's going on. If your teacher suddenly started quacking like a duck, the class would look at him incredulously. When a student gives the wrong answer to an easy question, the teacher might incredulously say, "What?" If you're feeling incredulous (disbelieving), then you're probably acting incredulously.

Definitions of incredulously

adv in an incredulous manner

“the woman looked up at her incredulously
disbelievingly, unbelievingly
believingly, credulously
in a credulous manner