dumbfound [ dúm fównd ] (3rd person present singular dumbfounds, present participle dumbfounding, past and past participle dumbfounded) or
dumfound [ dúm fównd ] (3rd person present singular dumfounds, present participle dumfounding, past and past participle dumfounded)
transitive and intransitive verb
Definition:
make somebody speechless: to make somebody temporarily speechless with astonishment