Incredulous

Part of speech: adjective (a.)

1. Not credulous; indisposed to admit or accept that which is related as true, skeptical; unbelieving. Bacon. A fantastical incredulous fool. Bp. Wilkins.

2. Indicating, or caused by, disbelief or incredulity. "An incredulous smile." Longfellow.

3. Incredible; not easy to be believed. [R.] Shak.