There are 14 words that start with 'motorb'.
| motorbus | motorbike |
| motorboat | motorbiked |
| motorbikes | motorboats |
| motorbuses | motorbiking |
| motorboated | motorboater |
| motorbusses | motorboaters |
| motorboating | motorboatings |
Note: These 14 words that start with 'motorb' are found from the USA & Canada version of the tournament Scrabble word list.