WordWeb Online

1. Strike with disgust or revulsion
   "The scandalous behavior of this married woman appalled her friends";
   - shock, offend, scandalize, scandalise [Brit], appal [Brit, Cdn], outrage
    
2. Fill with apprehension or alarm; cause to be unpleasantly surprised
   "I was appalled at the thought of being late for my interview";
   - dismay, alarm, appal [Brit, Cdn], horrify

Derived forms: appalls, appalling

Type of: affright, churn up, disgust, fright [archaic], frighten, nauseate, revolt, scare, sicken