There are 12 words that start with 'subso'.
| subsoil | subsoils | subsolar | 
| subsonic | subsocial | subsoiled | 
| subsoiler | subsociety | subsoilers | 
| subsoiling | subsocieties | subsonically | 
Note: These 12 words that start with 'subso' are found from the USA & Canada version of the tournament Scrabble word list.