siren isren srien rsien irsen risen siern isern seirn esirn iesrn eisrn srein rsein serin esrin resin ersin iresn riesn iersn eirsn reisn erisn sirne isrne srine rsine irsne risne sinre isnre snire nsire insre nisre srnie rsnie snrie nsrie rnsie nrsie irnse rinse inrse nirse rnise nrise sienr isenr seinr esinr iesnr eisnr siner isner snier nsier inser niser senir esnir sneir nseir ensir nesir iensr einsr inesr niesr enisr neisr sreni rseni serni esrni resni ersni srnei rsnei snrei nsrei rnsei nrsei senri esnri sneri nseri ensri nesri rensi ernsi rnesi nresi enrsi nersi irens riens ierns eirns reins erins irnes rines inres nires rnies nries ienrs einrs iners niers enirs neirs renis ernis rneis nreis enris neris
Note: these 'words' (valid or invalid) are all the permutations of the word siren. These words are obtained by scrambling the letters in siren.