xbol bxol xobl oxbl boxl obxl xblo bxlo xlbo lxbo blxo lbxo xolb oxlb xlob lxob olxb loxb bolx oblx blox lbox olbx lobx
Note: these 'words' (valid or invalid) are all the permutations of the word xbol. These words are obtained by scrambling the letters in xbol.