There are 10 words that start with 'diffr'.
| diffract | diffracts | 
| diffracted | diffracting | 
| diffraction | diffractions | 
| diffractometer | diffractometry | 
| diffractometers | diffractometric | 
Note: These 10 words that start with 'diffr' are found from the USA & Canada version of the tournament Scrabble word list.