ursae rusae usrae surae rsuae sruae urase ruase uarse aurse rause aruse usare suare uasre ausre saure asure rsaue sraue rasue arsue sarue asrue ursea rusea usrea surea rsuea sruea uresa ruesa uersa eursa reusa erusa usera suera uesra eusra seura esura rseua sreua resua ersua serua esrua uraes ruaes uares aures raues arues ureas rueas ueras euras reuas eruas uaers auers uears euars aeurs eaurs raeus areus reaus eraus aerus earus usaer suaer uaser auser sauer asuer usear suear uesar eusar seuar esuar uaesr auesr ueasr euasr aeusr eausr saeur aseur seaur esaur aesur easur rsaeu sraeu raseu arseu sareu asreu rseau sreau resau ersau serau esrau raesu aresu reasu erasu aersu earsu saeru aseru searu esaru aesru easru
Note: these 'words' (valid or invalid) are all the permutations of the word ursae. These words are obtained by scrambling the letters in ursae.