aback baack aabck aabck baack aback abcak bacak acbak cabak bcaak cbaak aacbk aacbk acabk caabk acabk caabk bacak abcak bcaak cbaak acbak cabak abakc baakc aabkc aabkc baakc abakc abkac bakac akbac kabac bkaac kbaac aakbc aakbc akabc kaabc akabc kaabc bakac abkac bkaac kbaac akbac kabac abcka backa acbka cabka bcaka cbaka abkca bakca akbca kabca bkaca kbaca ackba cakba akcba kacba ckaba kcaba bckaa cbkaa bkcaa kbcaa ckbaa kcbaa aackb aackb acakb caakb acakb caakb aakcb aakcb akacb kaacb akacb kaacb ackab cakab akcab kacab ckaab kcaab ackab cakab akcab kacab ckaab kcaab backa abcka bcaka cbaka acbka cabka bakca abkca bkaca kbaca akbca kabca bckaa cbkaa bkcaa kbcaa ckbaa kcbaa ackba cakba akcba kacba ckaba kcaba
Note: these 'words' (valid or invalid) are all the permutations of the word aback. These words are obtained by scrambling the letters in aback.