1.VerbTo overwhelm with bewilderment; to amaze, confound, or stun, especially in a ludicrous manner. .mw-parser-output .defdate{font-size:smaller}
"He was flabbergasted to find that his work had been done for him before he began.; Her stupidity flabbergasts me, and I have to force myself to keep a straight face while she explains her beliefs.; The oddity of the situation was so flabbergasting I couldn’t react in time for anyone to see it."
2.NounAn awkward person.
3.NounOverwhelming confusion, shock, or surprise.
"His flabbergast was so great he couldn’t even come up with a plausible answer."