wrack rwack warck awrck rawck arwck wrcak rwcak wcrak cwrak rcwak crwak wacrk awcrk wcark cwark acwrk cawrk racwk arcwk rcawk crawk acrwk carwk wrakc rwakc warkc awrkc rawkc arwkc wrkac rwkac wkrac kwrac rkwac krwac wakrc awkrc wkarc kwarc akwrc kawrc rakwc arkwc rkawc krawc akrwc karwc wrcka rwcka wcrka cwrka rcwka crwka wrkca rwkca wkrca kwrca rkwca krwca wckra cwkra wkcra kwcra ckwra kcwra rckwa crkwa rkcwa krcwa ckrwa kcrwa wackr awckr wcakr cwakr acwkr cawkr wakcr awkcr wkacr kwacr akwcr kawcr wckar cwkar wkcar kwcar ckwar kcwar ackwr cakwr akcwr kacwr ckawr kcawr rackw arckw rcakw crakw acrkw carkw rakcw arkcw rkacw kracw akrcw karcw rckaw crkaw rkcaw krcaw ckraw kcraw ackrw cakrw akcrw kacrw ckarw kcarw
Note: these 'words' (valid or invalid) are all the permutations of the word wrack. These words are obtained by scrambling the letters in wrack.