There are 13 words that start with 'combu'.
| combust | combusts | 
| combusted | combustor | 
| combusting | combustion | 
| combustive | combustors | 
| combustible | combustibly | 
| combustions | combustibles | 
| combustibility | |
Note: These 13 words that start with 'combu' are found from the USA & Canada version of the tournament Scrabble word list.