tifos itfos tfios ftios iftos fitos tiofs itofs toifs otifs iotfs oitfs tfois ftois tofis otfis fotis oftis ifots fiots iofts oifts foits ofits tifso itfso tfiso ftiso iftso fitso tisfo itsfo tsifo stifo istfo sitfo tfsio ftsio tsfio stfio fstio sftio ifsto fisto isfto sifto fsito sfito tiosf itosf toisf otisf iotsf oitsf tisof itsof tsiof stiof istof sitof tosif otsif tsoif stoif ostif sotif iostf oistf isotf siotf ositf soitf tfosi ftosi tofsi otfsi fotsi oftsi tfsoi ftsoi tsfoi stfoi fstoi sftoi tosfi otsfi tsofi stofi ostfi sotfi fosti ofsti fsoti sfoti osfti softi ifost fiost iofst oifst foist ofist ifsot fisot isfot sifot fsiot sfiot iosft oisft isoft sioft osift soift fosit ofsit fsoit sfoit osfit sofit
Note: these 'words' (valid or invalid) are all the permutations of the word tifos. These words are obtained by scrambling the letters in tifos.