C1 adjective /ˌʌnbɪˈliːvɪŋ/
unbelieving
incrédulo
Meaning
Not willing or able to believe; skeptical or doubtful
Example
She gave him an unbelieving look when he claimed to have met a celebrity.
Ella le dio una mirada incrédula cuando afirmó haber conocido a una celebridad.