neboc enboc nbeoc bneoc ebnoc benoc neobc enobc noebc onebc eonbc oenbc nboec bnoec nobec onbec bonec obnec ebonc beonc eobnc oebnc boenc obenc nebco enbco nbeco bneco ebnco benco necbo encbo ncebo cnebo ecnbo cenbo nbceo bnceo ncbeo cnbeo bcneo cbneo ebcno becno ecbno cebno bceno cbeno neocb enocb noecb onecb eoncb oencb necob encob nceob cneob ecnob cenob noceb onceb ncoeb cnoeb ocneb coneb eocnb oecnb econb ceonb ocenb coenb nboce bnoce nobce onbce bonce obnce nbcoe bncoe ncboe cnboe bcnoe cbnoe nocbe oncbe ncobe cnobe ocnbe conbe bocne obcne bcone cbone ocbne cobne ebocn beocn eobcn oebcn boecn obecn ebcon becon ecbon cebon bceon cbeon eocbn oecbn ecobn ceobn ocebn coebn bocen obcen bcoen cboen ocben coben
Note: these 'words' (valid or invalid) are all the permutations of the word neboc. These words are obtained by scrambling the letters in neboc.