Combinations of n different letters: n!

deaths = 6x5x4x3x2x1 = 720

thesad, sadeth, hasted, hadset, atheds, daeths, hsated, hsdtea, hteads, esdaht, hdtase, aedths, tdaseh, sehtad, daeths, athsed, tesdha, asetdh, athsde, dsathe, hdseta, saetdh, thades, htsade, dtseha, hatsde, shtade, deaths....

autopsy = 7! = 5040
ostayup, saypout, apusyto, yuspaot, otpsuya, yoptaus, aosptuy, utsopya, aptousy, yosutpa, ypostua, upaytos, utasopy, pyuasot, ptousay, upyaost, uoapyst, atsyupo, ptsuyao, ysaoput, ytaspou, syuatpo, suyapot, autopsy....

postmortem = 10!/3 = 3628800 = 1,209,600
motorstepm, temptrooms, opmrsmotet, teroostpmm, mptseotmro, pormeotsmt, omettomprs, roopmtmtes, mmeptsorto, momoetptrs, esmrtootmp, oresmpomtt, potsoemrmt, tpmtreosmo, sremmtpoto, postmortem...