safer asfer sfaer fsaer afser faser saefr asefr seafr esafr aesfr easfr sfear fsear sefar esfar fesar efsar afesr faesr aefsr eafsr feasr efasr safre asfre sfare fsare afsre fasre sarfe asrfe srafe rsafe arsfe rasfe sfrae fsrae srfae rsfae frsae rfsae afrse farse arfse rafse frase rfase saerf aserf searf esarf aesrf easrf saref asref sraef rsaef arsef rasef seraf esraf sreaf rseaf ersaf resaf aersf earsf aresf raesf erasf reasf sfera fsera sefra esfra fesra efsra sfrea fsrea srfea rsfea frsea rfsea serfa esrfa srefa rsefa ersfa resfa fersa efrsa fresa rfesa erfsa refsa afers faers aefrs eafrs fears efars afres fares arfes rafes fraes rfaes aerfs earfs arefs raefs erafs reafs feras efras freas rfeas erfas refas
Note: these 'words' (valid or invalid) are all the permutations of the word safer. These words are obtained by scrambling the letters in safer.