in·cred·u·lous /(ˌ)ɪnˈkrɛʤələs, djələs/
1. Not credulous; indisposed to admit or accept that which is related as true, skeptical; unbelieving.
A fantastical incredulous fool. --Bp. Wilkins.
2. Indicating, or caused by, disbelief or incredulity. “An incredulous smile.”
3. Incredible; not easy to be believed. [R.]
adj : not disposed or willing to believe; unbelieving [ant: credulous]