dumbfound
— Verb
– English
~ be a mystery or bewildering to; "This beats me!"; "Got me--I don't know the answer!"; "a vexing problem"; "This question really stuck me"
dumbfounded
— Adjective
– English
~ as if struck dumb with astonishment and surprise; "a circle of policemen stood dumbfounded by her denial of having seen the accident"; "the flabbergasted aldermen were speechless"; "was thunderstruck by the news of his promotion"
dumbstricken
— Adjective
– English
~ as if struck dumb with astonishment and surprise; "a circle of policemen stood dumbfounded by her denial of having seen the accident"; "the flabbergasted aldermen were speechless"; "was thunderstruck by the news of his promotion"