There are 8 words that start with 'dumbf'.
| dumbfound | dumbfounds |
| dumbfounded | dumbfounder |
| dumbfounders | dumbfounding |
| dumbfoundered | dumbfoundering |
Note: These 8 words that start with 'dumbf' are found from the USA & Canada version of the tournament Scrabble word list.