There are 12 words that start with 'swimm'.
| swimmy | swimmer | swimmers | 
| swimmier | swimmily | swimming | 
| swimmable | swimmeret | swimmiest | 
| swimmings | swimmerets | swimmingly | 
Note: These 12 words that start with 'swimm' are found from the USA & Canada version of the tournament Scrabble word list.