brook rbook borok obrok robok orbok brook rbook borok obrok robok orbok boork obork boork obork oobrk oobrk roobk orobk roobk orobk oorbk oorbk broko rboko borko obrko robko orbko brkoo rbkoo bkroo kbroo rkboo krboo bokro obkro bkoro kboro okbro kobro rokbo orkbo rkobo krobo okrbo korbo broko rboko borko obrko robko orbko brkoo rbkoo bkroo kbroo rkboo krboo bokro obkro bkoro kboro okbro kobro rokbo orkbo rkobo krobo okrbo korbo bookr obokr bookr obokr oobkr oobkr bokor obkor bkoor kboor okbor kobor bokor obkor bkoor kboor okbor kobor ookbr ookbr okobr koobr okobr koobr rookb orokb rookb orokb oorkb oorkb rokob orkob rkoob kroob okrob korob rokob orkob rkoob kroob okrob korob ookrb ookrb okorb koorb okorb koorb
Note: these 'words' (valid or invalid) are all the permutations of the word brook. These words are obtained by scrambling the letters in brook.