There are 17 words that start with 'clum'.
| clump | clumps | clumpy |
| clumsy | clumber | clumped |
| clumbers | clumpier | clumping |
| clumpish | clumsier | clumsily |
| clumpiest | clumplike | clumsiest |
| clumsiness | clumsinesses | |
Note: These 17 words that start with 'clum' are found from the USA & Canada version of the tournament Scrabble word list.