dunce udnce dnuce nduce undce nudce ducne udcne dcune cdune ucdne cudne dncue ndcue dcnue cdnue ncdue cndue uncde nucde ucnde cunde ncude cnude dunec udnec dnuec nduec undec nudec duenc udenc deunc edunc uednc eudnc dneuc ndeuc denuc ednuc neduc enduc unedc nuedc uendc eundc neudc enudc ducen udcen dcuen cduen ucden cuden duecn udecn deucn educn uedcn eudcn dceun cdeun decun edcun cedun ecdun ucedn cuedn uecdn eucdn ceudn ecudn dnceu ndceu dcneu cdneu ncdeu cndeu dnecu ndecu dencu edncu nedcu endcu dcenu cdenu decnu edcnu cednu ecdnu ncedu cnedu necdu encdu cendu ecndu unced nuced ucned cuned ncued cnued unecd nuecd uencd euncd neucd enucd ucend cuend uecnd eucnd ceund ecund nceud cneud necud encud cenud ecnud
Note: these 'words' (valid or invalid) are all the permutations of the word dunce. These words are obtained by scrambling the letters in dunce.