The Collaborative International Dictionary of English v.0.48:
Manslayer \Man"slay`er\, n. One who kills a human being; one who commits manslaughter. [1913 Webster]WordNet (r) 3.0 (2006):
manslayer n 1: a criminal who commits homicide (who performs the unlawful premeditated killing of another human being) [syn: murderer, liquidator, manslayer]