ap ‧ pal BrE AmE British English , appall American English /əˈpɔːl $ əˈpɒːl/ verb [transitive]
[ Date: 1500-1600 ; Language: Old French ; Origin: apalir , from palir 'to turn pale' ]
to make someone feel very shocked and upset SYN horrify :
The way we kill animals appals a lot of people.
The decision to execute the two men has appalled many politicians.