Why get hung up on language? It doesn't matter what you call it. If you haven't been drinking for a few days and start drinking again then that's a problem. And this is so whether it's a "relapse" or some other term. Let's just say that a person in that situation has begun to drink again and try to do something about that. What to do? Get help. From a doctor, from a group like AA, from a counselor, from another recovering alcoholic who has stayed sober.
W.