/ ɪnˈkredjələs; NAmE -dʒəl-/ adjective
not willing or not able to believe sth; showing an inability to believe sth :
'Here?' said Kate, incredulous.
an incredulous look
—compare credulous
► in·credu·lity / ˌɪnkrəˈdjuːləti; NAmE -ˈduː-/ noun [ U ]
SYN disbelief :
a look of surprise and incredulity
► in·credu·lous·ly adverb :
He laughed incredulously.
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WORD ORIGIN
16th cent.: from Latin incredulus (from in- not + credulus believing, trusting, from credere believe) + -ous .