(comparative more flabbergastingly, superlative most flabbergastingly)
- Surprisingly, astonishingly or amazingly
- It was a good date but the food at the restaurant was so flabbergastingly excellent I could barely think of anything else to talk about.
- He had said he would clean his room a thousand times before, but this time he actually did it, and flabbergastingly well too.
flabbergasting + -ly