WordWeb Online

1. Anything of great importance or consequence
    
2. An important influential person
   "she's a big deal in local politics";
   - big shot [informal], big gun [informal], big wheel [N. Amer, informal], big cheese [informal], big enchilada [informal], big fish [informal], head honcho [N. Amer, informal]

Type of: importance, important person, influential person, personage