incredulous

 
Pronunciation: /ɪnˈkrɛdjʊləs/

adjective

  • (of a person or their manner) unwilling or unable to believe something: an incredulous gasp

Derivatives

incredulously

adverb

incredulousness

noun

Origin:

16th century: from Latin incredulus (from in- 'not' + credulus 'believing, trusting', from credere 'believe') + -ous