preos rpeos peros epros repos erpos proes rpoes pores opres ropes orpes peors epors poers opers eoprs oeprs reops erops roeps oreps eorps oerps preso rpeso perso eprso repso erpso prseo rpseo psreo spreo rspeo srpeo pesro epsro psero spero espro sepro respo erspo rsepo srepo esrpo serpo prose rpose porse oprse ropse orpse prsoe rpsoe psroe sproe rspoe srpoe posre opsre psore spore ospre sopre rospe orspe rsope srope osrpe sorpe peosr eposr poesr opesr eopsr oepsr pesor epsor pseor speor espor sepor poser opser psoer spoer osper soper eospr oespr esopr seopr osepr soepr reosp erosp roesp oresp eorsp oersp resop ersop rseop sreop esrop serop rosep orsep rsoep sroep osrep sorep eosrp oesrp esorp seorp oserp soerp
Note: these 'words' (valid or invalid) are all the permutations of the word preos. These words are obtained by scrambling the letters in preos.