There are 15 words that start with 'dull'.
| dull | dulls | dully | 
| dulled | duller | dullard | 
| dullest | dulling | dullish | 
| dullards | dullness | dullishly | 
| dullnesses | dullsville | dullsvilles | 
Note: These 15 words that start with 'dull' are found from the USA & Canada version of the tournament Scrabble word list.