The Oxford Thesaurus An A-Z Dictionary of Synonyms - killern.

1) murderer, assassin, slayer, cutthroat, butcher, exterminator, Bluebeard, (Jack the) ripper, Slang US torpedo, hit man, triggerman, gunsel, hooligan, gunfighter, iceman, hatchet man: What are the statistics on the number of killers who are not caught? 2 Slang old-fashioned bee's knees, US humdinger, doozy, killer-diller (from Manila) , lallapalooza or lollapalooza, lulu, daisy, dilly: The new show at the Odeon is a killer.