nbatr bnatr nabtr anbtr bantr abntr nbtar bntar ntbar tnbar btnar tbnar natbr antbr ntabr tnabr atnbr tanbr batnr abtnr btanr tbanr atbnr tabnr nbart bnart nabrt anbrt banrt abnrt nbrat bnrat nrbat rnbat brnat rbnat narbt anrbt nrabt rnabt arnbt ranbt barnt abrnt brant rbant arbnt rabnt nbtra bntra ntbra tnbra btnra tbnra nbrta bnrta nrbta rnbta brnta rbnta ntrba tnrba nrtba rntba trnba rtnba btrna tbrna brtna rbtna trbna rtbna natrb antrb ntarb tnarb atnrb tanrb nartb anrtb nratb rnatb arntb rantb ntrab tnrab nrtab rntab trnab rtnab atrnb tarnb artnb ratnb tranb rtanb batrn abtrn btarn tbarn atbrn tabrn bartn abrtn bratn rbatn arbtn rabtn btran tbran brtan rbtan trban rtban atrbn tarbn artbn ratbn trabn rtabn
Note: these 'words' (valid or invalid) are all the permutations of the word nbatr. These words are obtained by scrambling the letters in nbatr.