istle sitle itsle tisle stile tsile islte silte ilste liste slite lsite itlse tilse iltse litse tlise ltise stlie tslie sltie lstie tlsie ltsie istel sitel itsel tisel stiel tsiel isetl sietl iestl eistl seitl esitl itesl tiesl ietsl eitsl teisl etisl steil tseil setil estil tesil etsil islet silet ilset liset sliet lsiet iselt sielt ieslt eislt seilt esilt ilest liest ielst eilst leist elist sleit lseit selit eslit lesit elsit itles tiles iltes lites tlies lties itels tiels ietls eitls teils etils ilets liets ielts eilts leits elits tleis lteis telis etlis letis eltis stlei tslei sltei lstei tlsei ltsei steli tseli setli estli tesli etsli sleti lseti selti eslti lesti elsti tlesi ltesi telsi etlsi letsi eltsi
Note: these 'words' (valid or invalid) are all the permutations of the word istle. These words are obtained by scrambling the letters in istle.