incredulous
in-KREJ-uh-lusadjMeaning unwilling or unable to believe something
Memory hook IN-CRED-ulous: “I can’t believe it!”. Kai says he cleaned his room, but Maya can see socks on the floor and books on the bed. Her raised eyebrows are incredulous.
Maya gave an incredulous laugh when her little brother said he had cleaned his room.
In context When the waiter announced that their meal was free, the diners were incredulous; they asked him three times whether he was joking.
Similar disbelieving, doubtful, skeptical, unconvinced
Opposite credulous, believing, trusting
From Latin incredulus: in (not) + credulus (believing).