unrid nurid urnid runid nruid rnuid unird nuird uinrd iunrd niurd inurd urind ruind uirnd iurnd riund irund nriud rniud nirud inrud rinud irnud unrdi nurdi urndi rundi nrudi rnudi undri nudri udnri dunri nduri dnuri urdni rudni udrni durni rduni druni nrdui rndui ndrui dnrui rdnui drnui unidr nuidr uindr iundr niudr inudr undir nudir udnir dunir nduir dnuir uidnr iudnr udinr duinr idunr diunr nidur indur ndiur dniur idnur dinur uridn ruidn uirdn iurdn riudn irudn urdin rudin udrin durin rduin druin uidrn iudrn udirn duirn idurn diurn ridun irdun rdiun driun idrun dirun nridu rnidu nirdu inrdu rindu irndu nrdiu rndiu ndriu dnriu rdniu drniu nidru indru ndiru dniru idnru dinru ridnu irdnu rdinu drinu idrnu dirnu
Note: these 'words' (valid or invalid) are all the permutations of the word unrid. These words are obtained by scrambling the letters in unrid.