A slaughterhouse is where animals are killed so they can be used for meat. Upton Sinclair’s 1906 novel The Jungle exposes the unsafe working conditions of a slaughterhouse in Chicago. Good times. Not.
In order for people to eat meat, animals have to be slaughtered, or killed, and the place where this happens on a large scale is a slaughterhouse. Sometimes it's also called an abattoir. The word stems from a Scandinavian root and is related to the Old Norseslatr, "a butchering." The word slaughterhouse can also refer to a violent situation. In Kurt Vonnegut's novel "Slaughterhouse Five," war prisoners are housed in an abandoned slaughterhouse, which is also a metaphor for war itself.