There are 3 14-letter words that end with 'ssing'.
| overimpressing | overprocessing | 
| teleprocessing | |
Note: These 3 14-letter words that end with 'ssing' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words end with essing, assing, ussing, ossing, issing.
7-letter words end with 'ssing' (24)