manslayer(n = noun.person) liquidator, murderer - a criminal who commits homicide (who performs the unlawful premeditated killing of another human being);
is a kind of criminal, crook, felon, malefactor, outlaw, killer, slayer
has particulars: assassin, assassinator, bravo, butcher, cutthroat, fratricide, gun, gun for hire, gunman, gunslinger, hired gun, hit man, hitman, shooter, torpedo, triggerman, hatchet man, iceman, infanticide, mass murderer, murderess, parricide, ripper, serial killer, serial murderer, jack the ripper

   One who kills a human being; one who commits manslaughter. [1913 Webster]