nugds ungds nguds gnuds ugnds gunds nudgs undgs ndugs dnugs udngs dungs ngdus gndus ndgus dngus gdnus dgnus ugdns gudns udgns dugns gduns dguns nugsd ungsd ngusd gnusd ugnsd gunsd nusgd unsgd nsugd snugd usngd sungd ngsud gnsud nsgud sngud gsnud sgnud ugsnd gusnd usgnd sugnd gsund sgund nudsg undsg ndusg dnusg udnsg dunsg nusdg unsdg nsudg snudg usndg sundg ndsug dnsug nsdug sndug dsnug sdnug udsng dusng usdng sudng dsung sdung ngdsu gndsu ndgsu dngsu gdnsu dgnsu ngsdu gnsdu nsgdu sngdu gsndu sgndu ndsgu dnsgu nsdgu sndgu dsngu sdngu gdsnu dgsnu gsdnu sgdnu dsgnu sdgnu ugdsn gudsn udgsn dugsn gdusn dgusn ugsdn gusdn usgdn sugdn gsudn sgudn udsgn dusgn usdgn sudgn dsugn sdugn gdsun dgsun gsdun sgdun dsgun sdgun
Note: these 'words' (valid or invalid) are all the permutations of the word nugds. These words are obtained by scrambling the letters in nugds.