IMO a drunk would be someone who likes a drink regularly, but doesn't necessarily 'need it' i.e. they don't start as soon as they wake up. In addition to this, I would also class a 'drunk' as someone who gets aggressive, domineering or uses the drink to get a false sense of confidence, which usually only portrays them as unsavoury to those around them. I've met plenty I would consider a drunk, a few closer to me than I'd like to admit, and I still avoid their company in drink where I can. This sort of drunk is the worst kind as I'm sure a lot of them do things and say things under the influence which they don't mean or would never do sober. Can be life destroying for those on the receiving end sadly.