Source : WordNet®

appal
     v 1: strike with disgust or revulsion; "The scandalous behavior
          of this married woman shocked her friends" [syn: {shock},
           {offend}, {scandalize}, {scandalise}, {appall}, {outrage}]
     2: fill with apprehension or alarm; cause to be unpleasantly
        surprised; "I was horrified at the thought of being late
        for my interview"; "The news of the executions horrified
        us" [syn: {dismay}, {alarm}, {appall}, {horrify}]
     [also: {appalling}, {appalled}]