ulmf lumf umlf mulf lmuf mluf ulfm lufm uflm fulm lfum flum umfl mufl ufml fuml mful fmul lmfu mlfu lfmu flmu mflu fmlu
Note: these 'words' (valid or invalid) are all the permutations of the word ulmf. These words are obtained by scrambling the letters in ulmf.