There are 7 words that start with 'exop'.
| exopeptidase | exophthalmic | 
| exophthalmos | exophthalmus | 
| exopeptidases | exophthalmoses | 
| exophthalmuses | |
Note: These 7 words that start with 'exop' are found from the USA & Canada version of the tournament Scrabble word list.