Source : WordNet®

flabbergasted
     adj : as if struck dumb with astonishment and surprise; "a circle
           of policement stood dumbfounded by her denial of having
           seen the accident"; "the flabbergasted aldermen were
           speechless"; "was thunderstruck by the news of his
           promotion" [syn: {dumbfounded}, {dumfounded}, {stupefied},
            {thunderstruck}]