present participle of flabbergaster

(colloquial) Bewildered shock or surprise; the state or condition of being flabbergasted. / (archaic, colloquial, humorous) The act of confounding or bewildering.

A person, thing, fact or event that is flabbergasting, or that causes extreme shock. / A state of surprise or fear.

(archaic) To perplex or amaze; to shock or frighten

Synonym of flabbergast (“overwhelming shock or surprise”)

in a flabbergasted manner.

Surprisingly, astonishingly or amazingly