tails atils tials itals aitls iatls talis atlis tlais ltais altis latis tilas itlas tlias ltias iltas litas ailts ialts alits laits ilats liats taisl atisl tiasl itasl aitsl iatsl tasil atsil tsail stail astil satil tisal itsal tsial stial istal sital aistl iastl asitl saitl isatl siatl talsi atlsi tlasi ltasi altsi latsi tasli atsli tsali stali astli satli tlsai ltsai tslai stlai lstai sltai alsti lasti aslti salti lsati slati tilsa itlsa tlisa ltisa iltsa litsa tisla itsla tsila stila istla sitla tlsia ltsia tslia stlia lstia sltia ilsta lista islta silta lsita slita ailst ialst alist laist ilast liast aislt iaslt asilt sailt isalt sialt alsit lasit aslit salit lsait slait ilsat lisat islat silat lsiat sliat
Note: these 'words' (valid or invalid) are all the permutations of the word tails. These words are obtained by scrambling the letters in tails.