flabbergasted
"Flabbergasted" means being extremely surprised or shocked, often to the point of being unable to speak or react immediately.
Matching Pairs
astonishedstunnedamazedspeechless
Examples
When I received the unexpected promotion at work, I was utterly flabbergasted and couldn't find the words to thank my boss.
She was flabbergasted to discover that her old college friend had become a best-selling author overnight.
As I entered the surprise party organized by my friends, I was flabbergasted to see everyone I knew from different parts of my life gathered together.