to slaughter: to kill an animal or a person by cutting the throat and draining the blood
At its core this word names one physical act: killing by the knife, with the throat cut and the blood let out. That single picture stretches across very different settings, which is why one word can sit at the center of Israel's worship and also describe a massacre.
Its heartland is the altar. This is the standard word for putting a sacrificial animal to death so its blood can be applied and its life offered. In the priestly instructions it appears again and again at the same moment of the ritual: the animal is brought, then it is slaughtered, then the blood is handled. Because the blood is the point, the word carries the sense of a deliberate, controlled killing.
Away from the altar the same act feeds people, when an animal is killed to be cooked and eaten, and it bends toward the killing of people, where it pictures cold, throat-cutting execution rather than the heat of battle. The prophets press on this overlap. When idolaters slaughter their own children, or when a worshiper who slaughters an ox is called no better than one who kills a man, the verb that belongs at the altar is turned into an accusation.