There are 12 10-letter words that start with 'sle'.
| sleazebags | sleazeball | sleaziness | 
| sleekening | sleepiness | sleepovers | 
| sleepwalks | sleepyhead | sleeveless | 
| sleevelets | slenderest | slenderize | 
Note: These 12 10-letter words that start with 'sle' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with slee, slea, sled, slen, slei, sleu, slew, slep.
4-letter words start with 'sle' (2)