Learn English – What would you call a person who is willing to give up their life for others

We do not have a specific noun that means "a person who would die for another person". The best we can do are words that describe more broadly such a person's traits and character. For instance, you could say someone is a hero (someone with great courage who does noble acts) or that they are selfless (they care less for themself than for others).

The closest English word for "giving up your life for someone else" would be sacrifice. To "sacrifice" means to give up something of value to you, usually for the sake of some ideal, belief, or other person/entity. This word is often used when someone dies for someone else, because what of greater value can you give up for someone else than your life?

We still run into problems with using this as a noun to "mean a person who is willing to die for someone else", though.

• Firstly, even as a noun, "sacrifice" is a direct reference to the action taken, as opposed to a trait or state of mind, so it only applies once it has actually occurred: being willing to endanger your life for someone else is not enough, you have to actually do it in order to be a sacrifice. If you want to talk about intent you have to use the verb form in a phase like this: "He is ready to sacrifice himself for her."
• Secondly, "sacrifice" is not usually used in noun form when referring to someone who is sacrificing themself. If you say someone is a "sacrifice" you usually mean that someone else is "sacrificing" them. (This is probably because of the word's link to religious practices involving killing a person or animal victim as an offering to a deity on behalf of someone else). Therefore, you probably wouldn't say: "Antonio was a sacrifice" if he died for you, because this implies you somehow did it to him on purpose or allowed it to happen. But you would say "Antonio sacrificed himself for me" or "Antonio made the sacrifice" or "Antonio was such a sacrificial person". In all of these cases the emphasis is changed slightly so that it is understood that Antonio chose to be a sacrifice for you, rather than that you forced him to be. We do have a derived term, self-sacrifice, that exists to help make this distinction, though you rarely hear this used as a noun applied to a person either. You might say "He is self-sacrificing" or "It was an act of self-sacrifice", but probably not "Antonio was a self-sacrifice."