incredulous (adj.)youdaoicibaDictYouDict[incredulous 词源字典]
"unbelieving," 1570s, from Latin incredulus "unbelieving, incredulous," from in- "not" (see in- (1)) + credulus (see credulous). Formerly also of religious beliefs. Related: Incredulously; incredulousness.[incredulous etymology, incredulous origin, 英语词源]