dumbfounded

From Wiktionary

Verb[change]

Plain form
dumbfound

Third-person singular
dumbfounds

Past tense
dumbfounded

Past participle
dumbfounded

Present participle
dumbfounding

  1. The past tense and past participle of dumbfound.

Adjective[change]

Positive
dumbfounded

Comparative
more dumbfounded

Superlative
most dumbfounded

  1. To be dumbfounded is to be shocked and lost for words.
    Nathan was left dumbfounded when he did not expect himself to score full marks for his science exams.