There are 11 15-letter words that end with 'iness'.
| blameworthiness | bloodguiltiness |
| crashworthiness | housewifeliness |
| fragmentariness | gentlemanliness |
| involuntariness | rudimentariness |
| perfunctoriness | persnicketiness |
| trustworthiness | |
Note: These 11 15-letter words that end with 'iness' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words end with liness, tiness, riness, kiness, hiness, diness, siness, piness, giness, niness, miness, ziness, finess, biness, ciness, winess, viness, xiness, ainess, uiness.
7-letter words end with 'iness' (1)