Another thing I wondered, was how big does a relapse have to be? Is it still a relapse whether it is one drink, or one night of drinking, or 7 months of active alcoholism and counting?
I think a "slip" (one drink or a night of drinking) is different from a relapse. (Or at least, it's different if the person is committed to recovery and re-commits after the one-drink, or one or more days of drinking.) I know a lot of people with good solid recovery who drank one or more times after their first attempt. They realized they had screwed up and got busy figuring out what they had missed in their recovery work. That's a lot different from a complete return to drinking (which is what I would consider a relapse).
I also don't consider it a relapse if you go a week without drinking and then drink again. After a week you haven't even started to recover, so all you really have is a one-week break in the pattern.