WordWeb Online

1. Extremely pleasing
   "a fab vacation";
   - fabulous
    
2. [Brit, informal] Brilliant; very good
   - socko [N. Amer, informal], righteous [US, slang], crucial [slang], rad [N. Amer, slang], radical [N. Amer, slang], nang [Brit, slang], phat [slang], legit [US, slang], awesomesauce [informal], amazeballs [informal], beaut [Austral, NZ, informal], lit [US, slang], storming [Brit, informal], blinding [Brit, slang], stonking [Brit, informal], brill [Brit, informal], wicked [slang], cushty [Brit, informal], ace [informal], def [slang], magic [Brit, slang], smokin' [slang], smoking [slang], super [informal], sick [N. Amer, slang]

See also: A1 [informal], ace [informal], A-one [informal], awesome [informal], beezer [UK, archaic], brilliant, crack [informal], excellent, fantabulous [informal], first-class, first-rate, lush [Brit, informal], mean [informal], outstanding, pleasing, ripping [Brit, informal], splendid, stellar [informal], super, tiptop, top-drawer, topnotch [informal], top-notch [informal], tops [informal]

Encyclopedia: Fab