a sacrifice: an animal killed as an offering to God whose meat is then eaten in a shared meal of worship
This word names a sacrifice by the one feature that sets it apart from every other kind: the animal is killed, its blood thrown against the altar and its fat burned for God, and then its meat is eaten. A burnt offering (עֹלָה) goes up entirely in smoke and no one tastes it; this is the sacrifice you actually sit down to. The offerer, his family, the priests, and his guests share the meal in God's presence, so the killing is only the means and the meal is the point. That is why the word so often marks a feast that binds people to God and to one another, from Jacob's pact with Laban to the elders eating before God at Sinai.
From that center the word reaches outward. It frequently stands for sacrifice in general, and is paired with the whole burnt offering (עֹלָה) to name the entire system of altar worship at once. The prophets and the Psalms then turn it on its edge, weighing the meat on the altar against the heart of the worshiper and insisting that God wants obedience, mercy, and a humbled spirit more than the offering itself.
The same word also covers, with open disapproval, the sacrifices people make to other gods. The act looks identical and the feast is the same; only the one being honored is wrong. The word itself stays neutral, and the surrounding text tells you whether the sacrifice is faithful or faithless.