There are 41 12-letter words that end with 'iness'.
Note: These 41 12-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)