sirens isrens sriens rsiens irsens risens sierns iserns seirns esirns iesrns eisrns sreins rseins serins esrins resins ersins iresns riesns iersns eirsns reisns erisns sirnes isrnes srines rsines irsnes risnes sinres isnres snires nsires insres nisres srnies rsnies snries nsries rnsies nrsies irnses rinses inrses nirses rnises nrises sienrs isenrs seinrs esinrs iesnrs eisnrs siners isners sniers nsiers insers nisers senirs esnirs sneirs nseirs ensirs nesirs iensrs einsrs inesrs niesrs enisrs neisrs srenis rsenis sernis esrnis resnis ersnis srneis rsneis snreis nsreis rnseis nrseis senris esnris sneris nseris ensris nesris rensis ernsis rnesis nresis enrsis nersis irenss rienss iernss eirnss reinss erinss irness riness inress niress rniess nriess ienrss einrss inerss nierss enirss neirss reniss erniss rneiss nreiss enriss neriss siresn isresn sriesn rsiesn irsesn risesn siersn isersn seirsn esirsn iesrsn eisrsn sreisn rseisn serisn esrisn resisn ersisn iressn riessn ierssn eirssn reissn erissn sirsen isrsen srisen rsisen irssen rissen sisren issren ssiren ssiren issren sisren srsien rssien ssrien ssrien rssien srsien irssen rissen isrsen sirsen rsisen srisen siesrn isesrn seisrn esisrn iessrn eissrn sisern issern ssiern ssiern issern sisern sesirn essirn sseirn sseirn essirn sesirn iessrn eissrn isesrn siesrn esisrn seisrn sresin rsesin sersin esrsin ressin erssin srsein rssein ssrein ssrein rssein srsein sesrin essrin sserin sserin essrin sesrin ressin erssin rsesin sresin esrsin sersin iressn riessn ierssn eirssn reissn erissn irsesn risesn isresn siresn rsiesn sriesn iesrsn eisrsn isersn siersn esirsn seirsn resisn ersisn rseisn sreisn esrisn serisn sirnse isrnse srinse rsinse irsnse risnse sinrse isnrse snirse nsirse insrse nisrse srnise rsnise snrise nsrise rnsise nrsise irnsse rinsse inrsse nirsse rnisse nrisse sirsne isrsne srisne rsisne irssne rissne sisrne issrne ssirne ssirne issrne sisrne srsine rssine ssrine ssrine rssine srsine irssne rissne isrsne sirsne rsisne srisne sinsre isnsre snisre nsisre inssre nissre sisnre issnre ssinre ssinre issnre sisnre snsire nssire ssnire ssnire nssire snsire inssre nissre isnsre sinsre nsisre snisre srnsie rsnsie snrsie nsrsie rnssie nrssie srsnie rssnie ssrnie ssrnie rssnie srsnie snsrie nssrie ssnrie ssnrie nssrie snsrie rnssie nrssie rsnsie srnsie nsrsie snrsie irnsse rinsse inrsse nirsse rnisse nrisse irsnse risnse isrnse sirnse rsinse srinse insrse nisrse isnrse sinrse nsirse snirse rnsise nrsise rsnise srnise nsrise snrise siensr isensr seinsr esinsr iesnsr eisnsr sinesr isnesr sniesr nsiesr insesr nisesr senisr esnisr sneisr nseisr ensisr nesisr ienssr einssr inessr niessr enissr neissr siesnr isesnr seisnr esisnr iessnr eissnr sisenr issenr ssienr ssienr issenr sisenr sesinr essinr sseinr sseinr essinr sesinr iessnr eissnr isesnr siesnr esisnr seisnr sinser isnser sniser nsiser insser nisser sisner issner ssiner ssiner issner sisner snsier nssier ssnier ssnier nssier snsier insser nisser isnser sinser nsiser sniser sensir esnsir snesir nsesir enssir nessir sesnir essnir ssenir ssenir essnir sesnir snseir nsseir ssneir ssneir nsseir snseir enssir nessir esnsir sensir nsesir snesir ienssr einssr inessr niessr enissr neissr iesnsr eisnsr isensr siensr esinsr seinsr insesr nisesr isnesr sinesr nsiesr sniesr ensisr nesisr esnisr senisr nseisr sneisr srensi rsensi sernsi esrnsi resnsi ersnsi srnesi rsnesi snresi nsresi rnsesi nrsesi senrsi esnrsi snersi nsersi ensrsi nesrsi renssi ernssi rnessi nressi enrssi nerssi sresni rsesni sersni esrsni ressni erssni srseni rsseni ssreni ssreni rsseni srseni sesrni essrni sserni sserni essrni sesrni ressni erssni rsesni sresni esrsni sersni srnsei rsnsei snrsei nsrsei rnssei nrssei srsnei rssnei ssrnei ssrnei rssnei srsnei snsrei nssrei ssnrei ssnrei nssrei snsrei rnssei nrssei rsnsei srnsei nsrsei snrsei sensri esnsri snesri nsesri enssri nessri sesnri essnri ssenri ssenri essnri sesnri snseri nsseri ssneri ssneri nsseri snseri enssri nessri esnsri sensri nsesri snesri renssi ernssi rnessi nressi enrssi nerssi resnsi ersnsi rsensi srensi esrnsi sernsi rnsesi nrsesi rsnesi srnesi nsresi snresi ensrsi nesrsi esnrsi senrsi nsersi snersi irenss rienss iernss eirnss reinss erinss irness riness inress niress rniess nriess ienrss einrss inerss nierss enirss neirss reniss erniss rneiss nreiss enriss neriss iresns riesns iersns eirsns reisns erisns irsens risens isrens sirens rsiens sriens iesrns eisrns iserns sierns esirns seirns resins ersins rseins sreins esrins serins irnses rinses inrses nirses rnises nrises irsnes risnes isrnes sirnes rsines srines insres nisres isnres sinres nsires snires rnsies nrsies rsnies srnies nsries snries iensrs einsrs inesrs niesrs enisrs neisrs iesnrs eisnrs isenrs sienrs esinrs seinrs insers nisers isners siners nsiers sniers ensirs nesirs esnirs senirs nseirs sneirs rensis ernsis rnesis nresis enrsis nersis resnis ersnis rsenis srenis esrnis sernis rnseis nrseis rsneis srneis nsreis snreis ensris nesris esnris senris nseris sneris
Note: these 'words' (valid or invalid) are all the permutations of the word sirens. These words are obtained by scrambling the letters in sirens.