There are 13 words that start with 'sinc'.
| since | sincere |
| sincerer | sinciput |
| sincerely | sincerest |
| sincerity | sincipita |
| sinciputs | sincipital |
| sincereness | sincerities |
| sincerenesses | |
Note: These 13 words that start with 'sinc' are found from the USA & Canada version of the tournament Scrabble word list.