Source : Webster's Revised Unabridged Dictionary (1913)

Manslayer \Man"slay`er\, n.
   One who kills a human being; one who commits manslaughter.

Source : WordNet®

manslayer
     n : a criminal who commits homicide (who performs the unlawful
         premeditated killing of another human being) [syn: {murderer},
          {liquidator}]