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