mrack rmack marck amrck ramck armck mrcak rmcak mcrak cmrak rcmak crmak macrk amcrk mcark cmark acmrk camrk racmk arcmk rcamk cramk acrmk carmk mrakc rmakc markc amrkc ramkc armkc mrkac rmkac mkrac kmrac rkmac krmac makrc amkrc mkarc kmarc akmrc kamrc rakmc arkmc rkamc kramc akrmc karmc mrcka rmcka mcrka cmrka rcmka crmka mrkca rmkca mkrca kmrca rkmca krmca mckra cmkra mkcra kmcra ckmra kcmra rckma crkma rkcma krcma ckrma kcrma mackr amckr mcakr cmakr acmkr camkr makcr amkcr mkacr kmacr akmcr kamcr mckar cmkar mkcar kmcar ckmar kcmar ackmr cakmr akcmr kacmr ckamr kcamr rackm arckm rcakm crakm acrkm carkm rakcm arkcm rkacm kracm akrcm karcm rckam crkam rkcam krcam ckram kcram ackrm cakrm akcrm kacrm ckarm kcarm
Note: these 'words' (valid or invalid) are all the permutations of the word mrack. These words are obtained by scrambling the letters in mrack.