The act of killing. Specifically:
The extensive, violent, bloody, or wanton destruction of life; carnage. On war and mutual slaughter bent. (milton)
The act of killing cattle or other beasts for market.
Synonym: Carnage, massacre, butchery, murder, havoc.
Origin: OE. Slautir, slaughter, slaghter, Icel. Slatr slain flesh, modified by OE. Slaught, slaht, slaughter, fr. AS. Sleaht a stroke, blow; both from the root of E. Slay. See Slay, and cf. Onslaught.