Why has religion used the word sacrifice as just another word for murder?

They say he is being "sacrificed"? What sacrifice? All i see is cold blooded brutal MURDER. Why does religion use sacrifice when its just another word for murder? If Jesus or the aztecs sacrificed someone and pulled their heart out, I dont see anything about it that could be a sacrifice or sacrificing anything. Its one one man killing another man and calling it something else with a different name. What do you think?