wrun rwun wurn uwrn ruwn urwn wrnu rwnu wnru nwru rnwu nrwu wunr uwnr wnur nwur unwr nuwr runw urnw rnuw nruw unrw nurw
Note: these 'words' (valid or invalid) are all the permutations of the word wrun. These words are obtained by scrambling the letters in wrun.