The Collaborative International Dictionary of English v.0.48:

Slaughter \Slaugh"ter\, v. t. [imp. & p. p. Slaughtered; p.
   pr. & vb. n. Slaughtering.]
   1. To visit with great destruction of life; to kill; to slay
      in battle.
      [1913 Webster]

            Your castle is surprised; your wife and babes
            Savagely slaughtered.                 --Shak.
      [1913 Webster]

   2. To butcher; to kill for the market, as beasts.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Slaughter \Slaugh"ter\, n. [OE. slautir, slaughter, slaghter,
   Icel. sl[=a]tr slain flesh, modified by OE. slaught, slaht,
   slaughter, fr. AS. sleaht a stroke, blow; both from the root
   of E. slay. See Slay, v. t., and cf. Onslaught.]
   The act of killing. Specifically:
   (a) The extensive, violent, bloody, or wanton destruction of
       life; carnage.
       [1913 Webster]

             On war and mutual slaughter bent.    --Milton.
       [1913 Webster]
   (b) The act of killing cattle or other beasts for market.
       [1913 Webster]

   Syn: Carnage; massacre; butchery; murder; havoc.
        [1913 Webster]

WordNet (r) 3.0 (2006):

slaughter
    n 1: the killing of animals (as for food)
    2: a sound defeat [syn: thrashing, walloping, debacle,
       drubbing, slaughter, trouncing, whipping]
    3: the savage and excessive killing of many people [syn:
       slaughter, massacre, mass murder, carnage,
       butchery]
    v 1: kill (animals) usually for food consumption; "They
         slaughtered their only goat to survive the winter" [syn:
         butcher, slaughter]
    2: kill a large number of people indiscriminately; "The Hutus
       massacred the Tutsis in Rwanda" [syn: massacre,
       slaughter, mow down]