There are 13 words that start with 'volum'.
| volume | volumed | 
| volumes | voluming | 
| volumeter | volumeters | 
| volumetric | voluminous | 
| voluminosity | voluminously | 
| volumetrically | voluminosities | 
| voluminousness | |
Note: These 13 words that start with 'volum' are found from the USA & Canada version of the tournament Scrabble word list.