There are 14 12-letter words that start with 'san'.
| sanctimonies | sanctionable | sandblasters | 
| sandblasting | sandpainting | sandpapering | 
| sanguinarias | sanguinarily | sanguineness | 
| sanguinities | sanitization | sansculottes | 
| sansculottic | sansevierias | |
Note: These 14 12-letter words that start with 'san' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with sand, sani, sant, sang, sanc, sans, sane, sann, sana, sanb, sanj, sank.
4-letter words start with 'san' (5)