derth edrth dreth rdeth erdth redth detrh edtrh dterh tderh etdrh tedrh drteh rdteh dtreh tdreh rtdeh trdeh ertdh retdh etrdh terdh rtedh tredh derht edrht dreht rdeht erdht redht dehrt edhrt dhert hdert ehdrt hedrt drhet rdhet dhret hdret rhdet hrdet erhdt rehdt ehrdt herdt rhedt hredt dethr edthr dtehr tdehr etdhr tedhr dehtr edhtr dhetr hdetr ehdtr hedtr dther tdher dhter hdter thder htder ethdr tehdr ehtdr hetdr thedr htedr drthe rdthe dtrhe tdrhe rtdhe trdhe drhte rdhte dhrte hdrte rhdte hrdte dthre tdhre dhtre hdtre thdre htdre rthde trhde rhtde hrtde thrde htrde erthd rethd etrhd terhd rtehd trehd erhtd rehtd ehrtd hertd rhetd hretd ethrd tehrd ehtrd hetrd therd hterd rthed trhed rhted hrted thred htred
Note: these 'words' (valid or invalid) are all the permutations of the word derth. These words are obtained by scrambling the letters in derth.