There are 14 words that start with 'grump'.
| grump | grumps | grumpy |
| grumped | grumphy | grumphie |
| grumpier | grumpily | grumping |
| grumpish | grumphies | grumpiest |
| grumpiness | grumpinesses | |
Note: These 14 words that start with 'grump' are found from the USA & Canada version of the tournament Scrabble word list.