exnl xenl enxl nexl xnel nxel exln xeln elxn lexn xlen lxen enlx nelx elnx lenx nlex lnex xnle nxle xlne lxne nlxe lnxe
Note: these 'words' (valid or invalid) are all the permutations of the word exnl. These words are obtained by scrambling the letters in exnl.