There are 13 14-letter words that start with 'ill'.
| illegalization | illegibilities | 
| illegitimacies | illegitimately | 
| illiberalities | illimitability | 
| illiterateness | illogicalities | 
| illuminatingly | illusivenesses | 
| illusorinesses | illustrational | 
| illustratively | |
Note: These 13 14-letter words that start with 'ill' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with illu, illi, ille, illo, illa, illn, ills, illy.
4-letter words start with 'ill' (2)