There are 15 words that end with 'stness'.
| lostness | gastness |
| fastness | justness |
| pastness | vastness |
| moistness | firstness |
| augustness | robustness |
| unjustness | earnestness |
| colorfastness | lightfastness |
| steadfastness | |
Note: These 15 words that end with 'stness' are found from the USA & Canada version of the tournament Scrabble word list.