afncu fancu anfcu nafcu fnacu nfacu afcnu facnu acfnu cafnu fcanu cfanu ancfu nacfu acnfu canfu ncafu cnafu fncau nfcau fcnau cfnau ncfau cnfau afnuc fanuc anfuc nafuc fnauc nfauc afunc faunc aufnc uafnc fuanc ufanc anufc naufc aunfc uanfc nuafc unafc fnuac nfuac funac ufnac nufac unfac afcun facun acfun cafun fcaun cfaun afucn faucn aufcn uafcn fuacn ufacn acufn caufn aucfn uacfn cuafn ucafn fcuan cfuan fucan ufcan cufan ucfan ancuf nacuf acnuf canuf ncauf cnauf anucf naucf auncf uancf nuacf unacf acunf caunf aucnf uacnf cuanf ucanf ncuaf cnuaf nucaf uncaf cunaf ucnaf fncua nfcua fcnua cfnua ncfua cnfua fnuca nfuca funca ufnca nufca unfca fcuna cfuna fucna ufcna cufna ucfna ncufa cnufa nucfa uncfa cunfa ucnfa
Note: these 'words' (valid or invalid) are all the permutations of the word afncu. These words are obtained by scrambling the letters in afncu.