There are 16 words that start with 'ecum'.
| ecumenic | ecumenics | 
| ecumenism | ecumenist | 
| ecumenical | ecumenisms | 
| ecumenists | ecumenicism | 
| ecumenicist | ecumenicity | 
| ecumenically | ecumenicisms | 
| ecumenicists | ecumenicalism | 
| ecumenicities | ecumenicalisms | 
Note: These 16 words that start with 'ecum' are found from the USA & Canada version of the tournament Scrabble word list.