There are 14 words that start with 'stimu'.
| stimuli | stimulus | stimulant | 
| stimulate | stimulants | stimulated | 
| stimulates | stimulator | stimulating | 
| stimulation | stimulative | stimulators | 
| stimulatory | stimulations | |
Note: These 14 words that start with 'stimu' are found from the USA & Canada version of the tournament Scrabble word list.