WordWeb Online

1. Discouraging through fear
   "The tension was heightened by meetings that were fairly intimidating in their office or motel conference room settings";
   - daunting

1. Make timid or fearful
   "Her boss intimidates her"
    
2. To compel or deter by (or as if) by threats or a show of force
   - put the frigheners on [Brit, informal], put the screws on [informal]

See also: discouraging

Type of: affright, discourage, fright [archaic], frighten, frustrate, scare

Encyclopedia: Intimidating