appalyoudaoicibaDictYouDict[appal 词源字典]
"Greatly dismay or horrify", Middle English: from Old French apalir 'grow pale', from a- (from Latin ad 'to, at') + palir 'to pale'. The original sense was 'grow pale', later 'make pale', hence 'horrify' ( late Middle English). More Like abhor, appal has its origin in the physical effect of being horrified. Old French apalir meant both ‘to grow pale’ and ‘to make pale’, and these senses were carried over into the English word in the 14th century. As shock or disgust can make the colour drain from your face, appal soon acquired its current meaning.[appal etymology, appal origin, 英语词源]