'Sin offering' in the Bible

But the flesh of the ox and its skin and its waste parts are to be burned outside the circle of the tents, for it is a sin-offering.

Every day an ox is to be offered as a sin-offering, to take away sins: and by this offering on it, you will make the altar clean from sin; and you are to put oil on it and make it holy.

And once every year Aaron is to make its horns clean: with the blood of the sin-offering he is to make it clean once every year from generation to generation: it is most holy to the Lord.