There are 9 12-letter words that start with 'stu'.
| stubbornness | studentships | studiousness |
| stuffinesses | stupefaction | stupefyingly |
| stupendously | stupidnesses | sturdinesses |
Note: These 9 12-letter words that start with 'stu' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with stud, stup, stum, stun, stub, stuf, stur, stuc, stul, stut, stui.
4-letter words start with 'stu' (4)