There are 12 words that start with 'frus'.
| frusta | frustum | 
| frustule | frustums | 
| frustrate | frustules | 
| frustrated | frustrates | 
| frustrating | frustration | 
| frustrations | frustratingly | 
Note: These 12 words that start with 'frus' are found from the USA & Canada version of the tournament Scrabble word list.