There are 15 words that start with 'synthe'.
| syntheses | synthesis | 
| synthetic | synthesist | 
| synthesize | synthetase | 
| synthetics | synthesists | 
| synthesized | synthesizer | 
| synthesizes | synthetases | 
| synthesizers | synthesizing | 
| synthetically | |
Note: These 15 words that start with 'synthe' are found from the USA & Canada version of the tournament Scrabble word list.