The Collaborative International Dictionary of English v.0.48:

Homicide \Hom"i*cide\, n. [F., fr. L. homicidium, fr. homicida a
   man slayer; homo man + caedere to cut, kill. See Homage,
   and cf. Concise, Shed, v. t.]
   1. The killing of one human being by another.
      [1913 Webster]

   Note: Homicide is of three kinds: justifiable, as when the
         killing is performed in the exercise of a right or
         performance of a duty; excusable, as when done,
         although not as duty or right, yet without culpable or
         criminal intent; and felonious, or involving what the
         law terms malice; the latter may be either manslaughter
         or murder. --Bouvier.
         [1913 Webster]

   2. One who kills another; a manslayer. --Chaucer. Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

homicide
    n 1: the killing of a human being by another human being

The Devil's Dictionary (1881-1906):

HOMICIDE, n.  The slaying of one human being by another.  There are
four kinds of homocide:  felonious, excusable, justifiable, and
praiseworthy, but it makes no great difference to the person slain
whether he fell by one kind or another -- the classification is for
advantage of the lawyers.