WordWeb Online

1. Strike with disgust or revulsion
   "The scandalous behaviour of this married woman appalled her friends";
   - shock, offend, scandalize, scandalise [Brit], appall [US], 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, appall [US], horrify

Derived forms: appalling, appals

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