There are 4 15-letter words that start with 'enc'.
| encephalitogens | encephalographs | 
| encephalography | encephalopathic | 
Note: These 4 15-letter words that start with 'enc' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with enca, enco, ench, encr, ency, encl, enci, ence, encu.
6-letter words start with 'enc' (8)