rubin urbin rbuin bruin ubrin burin ruibn uribn riubn irubn uirbn iurbn rbiun briun ribun irbun birun ibrun ubirn buirn uibrn iubrn biurn iburn rubni urbni rbuni bruni ubrni burni runbi urnbi rnubi nrubi unrbi nurbi rbnui brnui rnbui nrbui bnrui nbrui ubnri bunri unbri nubri bnuri nburi ruinb urinb riunb irunb uirnb iurnb runib urnib rnuib nruib unrib nurib rinub irnub rniub nriub inrub nirub uinrb iunrb unirb nuirb inurb niurb rbinu brinu ribnu irbnu birnu ibrnu rbniu brniu rnbiu nrbiu bnriu nbriu rinbu irnbu rnibu nribu inrbu nirbu binru ibnru bniru nbiru inbru nibru ubinr buinr uibnr iubnr biunr ibunr ubnir bunir unbir nubir bnuir nbuir uinbr iunbr unibr nuibr inubr niubr binur ibnur bniur nbiur inbur nibur
Note: these 'words' (valid or invalid) are all the permutations of the word rubin. These words are obtained by scrambling the letters in rubin.