dumbfounding

/dʌmˈfaʊndɪŋ/
adjective
  1. Causing great surprise or confusion; astonishing.
    • It was dumbfounding to see how quickly the city rebuilt after the storm.
    • His dumbfounding ignorance of basic math shocked the tutor.
    • The dumbfounding news of the lottery win made her drop her coffee.
verb
  1. Present participle of dumbfound: to cause someone to become speechless with surprise or confusion.
    • The detective was dumbfounding the suspect with unexpected questions.
    • The magician kept dumbfounding the audience with each new trick.
    • She is dumbfounding her colleagues by solving problems no one else could.