atfcu tafcu aftcu fatcu tfacu ftacu atcfu tacfu actfu catfu tcafu ctafu afctu factu acftu caftu fcatu cfatu tfcau ftcau tcfau ctfau fctau cftau atfuc tafuc aftuc fatuc tfauc ftauc atufc taufc autfc uatfc tuafc utafc afutc fautc auftc uaftc fuatc ufatc tfuac ftuac tufac utfac futac uftac atcuf tacuf actuf catuf tcauf ctauf atucf taucf autcf uatcf tuacf utacf acutf cautf auctf uactf cuatf ucatf tcuaf ctuaf tucaf utcaf cutaf uctaf afcut facut acfut cafut fcaut cfaut afuct fauct aufct uafct fuact ufact acuft cauft aucft uacft cuaft ucaft fcuat cfuat fucat ufcat cufat ucfat tfcua ftcua tcfua ctfua fctua cftua tfuca ftuca tufca utfca futca uftca tcufa ctufa tucfa utcfa cutfa uctfa fcuta cfuta fucta ufcta cufta ucfta
Note: these 'words' (valid or invalid) are all the permutations of the word atfcu. These words are obtained by scrambling the letters in atfcu.