There are 9 11-letter words that start with 'fis'.
| fishability | fisherwoman | fisherwomen | 
| fishinesses | fishmongers | fishtailing | 
| fissilities | fissionable | fissiparous | 
Note: These 9 11-letter words that start with 'fis' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with fish, fiss, fist, fisc.
4-letter words start with 'fis' (3)