WordWeb Online

1. So great in size or force or extent as to elicit awe
   "a prodigious storm"
   - colossal, stupendous
    
2. Of momentous or ominous significance
   "a prodigious vision"
   - portentous
    
3. Far beyond what is usual in magnitude or degree
   "the young Mozart's prodigious talents"
   - exceeding, exceptional, olympian, surpassing

See also: big, extraordinary, important, large, prodigiously, prodigy, significant

Encyclopedia: Prodigious