dumbfound
verb /dʌmˈfaʊnd/
  /dʌmˈfaʊnd/
 Verb Forms
| present simple I / you / we / they dumbfound |  /dʌmˈfaʊnd/  /dʌmˈfaʊnd/ | 
| he / she / it dumbfounds |  /dʌmˈfaʊndz/  /dʌmˈfaʊndz/ | 
| past simple dumbfounded |  /dʌmˈfaʊndɪd/  /dʌmˈfaʊndɪd/ | 
| past participle dumbfounded |  /dʌmˈfaʊndɪd/  /dʌmˈfaʊndɪd/ | 
| -ing form dumbfounding |  /dʌmˈfaʊndɪŋ/  /dʌmˈfaʊndɪŋ/ | 
- dumbfound somebody to surprise or shock somebody so much that they are unable to speak- His reply dumbfounded me.