treks rteks terks etrks retks ertks trkes rtkes tkres ktres rktes krtes tekrs etkrs tkers kters ektrs ketrs rekts erkts rkets krets ekrts kerts tresk rtesk tersk etrsk retsk ertsk trsek rtsek tsrek strek rstek srtek tesrk etsrk tserk sterk estrk setrk restk erstk rsetk sretk esrtk sertk trkse rtkse tkrse ktrse rktse krtse trske rtske tsrke strke rstke srtke tksre ktsre tskre stkre kstre sktre rkste krste rskte srkte ksrte skrte teksr etksr tkesr ktesr ektsr ketsr teskr etskr tsekr stekr estkr setkr tkser ktser tsker stker kster skter ekstr kestr esktr sektr ksetr sketr rekst erkst rkest krest ekrst kerst reskt erskt rsekt srekt esrkt serkt rkset krset rsket srket ksret skret eksrt kesrt eskrt sekrt ksert skert
Note: these 'words' (valid or invalid) are all the permutations of the word treks. These words are obtained by scrambling the letters in treks.