The verb appall has 2 senses (no senses from tagged texts)
1. shock, offend, scandalize, scandalise, appal, appall, outrage -- (strike with disgust or revulsion; "The scandalous behavior of this married woman shocked her friends")
2. dismay, alarm, appal, appall, horrify -- (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")