Definition of flabbergast in English:

flabbergast

verb

[WITH OBJECT]usually as adjective flabbergasted
informal
  • Surprise (someone) greatly; astonish:

    ‘this news has left me totally flabbergasted’
    • ‘And she is flabbergasted the police have said they cannot act against the owner because the dogs are not registered as dangerous.’
    • ‘A shopkeeper was flabbergasted when he opened his mail to find an apology from a shoplifter, with a cheque for £75.’
    • ‘Today Ms Morris said she was flabbergasted by the award.’
    • ‘Well, I'd just like to say that I'm completely flabbergasted and astounded.’
    • ‘I was flabbergasted to learn how much of our money is being wasted in this way.’
    • ‘I am frankly flabbergasted that my complaints so far have proved so ineffectual.’
    • ‘I am flabbergasted at the crassness of things said to, and about, him this past week.’
    • ‘He was flabbergasted at the total complexity of the question.’
    • ‘I know there's a million puns to be had here, but I'm too flabbergasted to think of anything good.’
    • ‘I thought at first it must be a joke but apparently it's true and I am absolutely flabbergasted.’
    • ‘On the other hand, I am utterly flabbergasted that, if the argument is valid, I have not heard about it.’
    • ‘This effect is so obvious to me that I'm flabbergasted at the smart people who can't see it.’
    • ‘When she told me just a few weeks before that she was going to leave, I was flabbergasted and heartbroken.’
    • ‘I was flabbergasted afterwards to hear that they do eight shows a week.’
    • ‘Brian was flabbergasted, but not really surprised, not on a subconscious level.’
    • ‘When I found out that I'd got the part I was absolutely flabbergasted.’
    • ‘After a long wait, we're flabbergasted to be announced winners.’
    • ‘I was too flabbergasted to say anything, and later I felt guilty about that.’
    • ‘When they arrived she said she was flabbergasted at reading the cover page on them.’
    • ‘Mrs Lewis said she was flabbergasted at some of what she said.’
    astonish, astound, amaze, surprise, startle, shock, take aback, take by surprise
    dumbfound, strike dumb, render speechless, stun, stagger, stop someone in their tracks, take someone's breath away, confound, daze, overcome, overwhelm, nonplus, stupefy, disconcert, unsettle, bewilder
    bowl over, knock for six, knock sideways, knock the stuffing out of, floor
    gobsmack
    View synonyms

Origin

Late 18th century: of unknown origin.

Pronunciation:

flabbergast

/ˈflabəɡɑːst/