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

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "homicide":
   Cain, aborticide, apache, assassin, assassination, assassinator,
   blood, bloodletter, bloodshedder, bloody murder, bravo,
   bumping-off, burker, butcher, button man, cannibal, cutthroat,
   desperado, elimination, eradicator, executioner, exterminator,
   foul play, fratricide, fungicide, garroter, genocide, germicide,
   gorilla, gun, gunman, gunsel, hatchet man, head-hunter, herbicide,
   hit man, homicidal maniac, infanticide, insecticide, killer,
   killing, liquidation, man-eater, man-killer, manslaughter,
   manslayer, massacrer, matador, matricide, microbicide, murder,
   murderer, parricide, patricide, pesticide, poison, poisoner, purge,
   purging, regicide, removal, rodenticide, slaughterer, slayer,
   sororicide, strangler, suicide, thug, thuggee, thuggery, thuggism,
   torpedo, trigger man, uxoricide, vermicide



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HOMICIDE, crim. law. According to Blackstone, it is the killing of any human
creature. 4 Com. 177. This is the most extensive sense of this word, in
which the intention is not considered. But in a more limited sense, it is
always understood that the killing is by human agency, and Hawkins defines
it to be the killing of a man by a man. 1 Hawk. c. 8, s. 2. See Dalloz,
Dict. h.t. Homicide may perhaps be described to be the destruction of the
life of one human being, either by himself, or by the act, procurement, or
culpable omission of another. When the death has been intentionally caused
by the deceased himself, the offender is called felo de se; when it is
caused by another, it is justifiable, excusable, or felonious.
     2. The person killed must have been born; the killing before birth is
balled foeticide. (q.v.)
     3. The destruction of human life at any period after birth, is
homicide, however near it may be to extinction, from any other cause.
     4.-1. Justifiable homicide is such as arises, 1st. From unavoidable
necessity, without any will, intention or desire, and without any
inadvertence in the party killing, and therefore without blame; as, for
instance, the execution, according to law, of a criminal who has been
lawfully sentenced to be hanged; or, 2d. It is committed for the advancement
of public justice; as if an officer, in the lawful execution of his office,
either in a civil or criminal case, should kill a person who assaults and
resists him. 4 Bl. Com. 178-1 80. See Justifiable Homicide.
     5.-2. Excusable homicide is of two kinds 1st. Homicide per
infortunium. (q.v.) or, 2d. Se defendendo, or self defence. (q.v.) 4 Bl.
Com. 182, 3.
     6.-3. Felonious homicide, which includes, 1. Self-murder, or suicide;
2. Man-slaughter, (q.v.); and, 3. Murder. (q.v.) Vide, generally, 3 Inst.
47 to 57; 1 Hale P. C. 411 to 602; 1 Hawk. c. 8; Fost. 255 to 837; 1 East,
P. C. 214 to 391; Com. Dig. Justices, L. M.; Bac. Ab. Murder and Homicide;
Burn's Just. h.t.; Williams' Just. h.t.; 2 Chit. Cr. Law, ch. 9; Cro. C.
C. 285 to 300; 4 Bl. Com. to 204; 1 Russ. Cr. 421 to 553; 2 Swift's Dig. 267
to 292.



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.