There are 17 words that start with 'calcu'.
| calculi | calculus | 
| calculate | calculous | 
| calculable | calculated | 
| calculates | calculator | 
| calculuses | calculating | 
| calculation | calculators | 
| calculatedly | calculations | 
| calculatingly | calculational | 
| calculatedness | |
Note: These 17 words that start with 'calcu' are found from the USA & Canada version of the tournament Scrabble word list.