incredulous
https://gyazo.com/d0341e51ca7287dd4860dba48bbe9984
source: 桃矢がケロベロスの存在を疑うGIF画像｜無料GIF画像検索 GIFMAGAZINE 780416
adjective
(of a person or their manner) unwilling or unable to believe something:
〈人が〉疑い深い; 〈顔つきなどが〉信じていない, 疑うような
e.g. an incredulous gasp.
DERIVATIVES
incredulousness | inˈkrejələsnəs | noun
USAGE
See usage at incredible.
ORIGIN
16th century: from Latin incredulus (from in- ‘not’ + credulus ‘believing, trusting’, from credere ‘believe’) + -ous.