flabbergasted UK /ˈflæbə(ˌ)ɡɑːstəd/US /ˈflæbɚˌɡæstəd/ adjective2 •Appalled, annoyed, exhausted or disgusted.He was flabbergasted at how much weight he had gained. •(euphemistic, rare) Damned. formsmore flabbergasted · most flabbergasted