A Samaritan is someone who helps you when you are in trouble — especially a stranger who stops, even though they do not have to. English got this from a story Jesus tells: a man is beaten on the road; religious people walk past; a man from Samaria binds his wounds and pays for his care. Jews and Samaritans in that story did not get along, so the shock is that the helper is the outsider. Today people say a good Samaritan more often than a bare Samaritan for this kind sense. It can also sit in front of a noun: a Samaritan act, Good Samaritan laws (rules that try to protect you if you give first aid to a stranger). Though actually, Samaritans are still a real, small religious people; the everyday English word has floated partly free of that, and now mostly means “kind stranger.” It feels a little formal or story-like — kind, not slangy.