"Sober" is commonly used by recovering/recovered alcoholics to mean they are no longer drinking. It implies that they were drinking too much, to the point where intoxication was a semi-permanent state. I've heard the word used this way for decades and I'm pretty sure it goes back farther.

Twelve-step groups have been using ''sober'' and ''sobriety'' for almost 100 years. In this day and age its surprising to see some confusion about what those terms can mean.

To be fair, I've never had an issue with drinking. I stopped in my mid twenties and haven't a drink in 20 years. But I never say I'm "sober" since that kind of insinuates it was a problem at one point. If someone offers me a drink, I just say "no thanks I don't drink."