WordWeb Online

1. Extremely pleasing
   "a fabulous vacation"
   - fab
    
2. Based on or told of in traditional stories; lacking factual basis or historical validity
   "the fabulous unicorn"
   - mythic, mythical, mythologic, mythological
    
3. Barely credible
   "the fabulous endurance of a marathon runner"

See also: fable, incredible, pleasing, unbelievable, unreal

Encyclopedia: Fabulous