I *highly* recommend the book, "In the Realm of Hungry Ghosts," by Gabor Mate, MD. http://www.amazon.com/s/ref=nb_sb_ss_i_1_11?url=search-al...
It is a book that gives a most comprehensive description and understanding of addiction - medically, psychologically, and internally. An *amazing* book.
Addiction is, in MY mind, not defined by quantity or by regularity of use. In my mind, there is no simple equation that allows us to know if someone else is/is not an addict. It's really up to them to determine that for themselves. That's not to say we don't get to identify behaviors, or to set healthy boundaries for ourselves.
I've known (self identified) alcoholics who drank once every few weeks. I've known (self identified) alcoholics who drank all day, every day. I've known alcoholics who were mean when they drank, who lost their families, who lost their jobs, and I've known alcoholics who got promotions during active addiction and who were nicer when drinking. In my mind, addiction is about the hunger, the obsession, the need for something external. It's about the way our brains relate to dopamine, and about how we cope with stimulation/trauma.
All of that to say, I don't think there is one answer to "what is alcoholism". If your husband is an alcoholic? That's for him to decide. What your husband decides to do with this is ultimately up to him. Now, that's not to say that you have to/will be fine with what he decides. Rather, it's not your responsibility to make that set of choices FOR him. It's your responsibility to make those choices for yourself.
For example: "It bothers me when they get drunk". I don't get to make sure my spouses doesn't use / or to decide what is a problem for HIM, but I do think I get to my own boundaries.
For example, *I* don't (often) feel good when I choose to be around drunk folks. *I* don't feel good when I'm around heavy drinking, so I choose not to be around it. Then again, my boundaries are fluid. I chose to spend time with my dad a few weeks ago, even though he was drinking. My choice. I chose to go out dancing with some girlfriends and we went to the bar strip to do so. My choice. I have done some harm reduction advocacy and would be around addicted populations. My choice. When I choose not to be around someone who is drinking, it has *everything* to do with me, and zero to do with them (unless they are crossing my boundaries after I've clearly stated and acted on them).
I'll give you a silly example. I hate the color beige. I mean, I really despise it. I don't get to make everyone else stop wearing beige, but I do get to decide that the color doesn't make it's way into my closet, and I do get to decide that I don't decorate in beige. I get to decide what is problematic for ME, and I get to have fluid boundaries.
I've chosen not to have an active relationship with my (actively addicted) sister. I don't like being around her. She gets to do what she wants, but she doesn't get to bring it into my life, because I've set boundaries. (I really love my sister, BTW.) I have chosen to keep our relationship at arms length because it feels damaging to have too much contact with her. On the other hand, I will write her occasionally, and today I will call the hospital to see if she's there - so it's fluid. And, I'm still learning ;-)
I choose to have a relationship with my (actively addicted) Dad. It's worth it to me, and I don't mind being around him when he's drinking. I don't have to have my kids around him when he's drinking. That's also up to me.
I choose to have a relationship with my (not actively using) husband. I chose not to be in a relationship with my husband when he's using, because I despise being around him when he's using.
Heck, it doesn't have to be substances, it can be behaviors. I don't have to be around a girlfriend of mine when she's controlling the whole darn world. I don't have to be around anyone whom I don't want. There are options. They may still be part of my life (my sister for example) but I don't need to invite them into my home, or my everyday life.
My suggestion, from my own POV, is that you may find relief if you don't try to determine what his path looks like. Rather than, "you should go to rehab / AA / outpatient", you might choose to say, "I feel _______ (sad, scared, annoyed, frustrated, X,Y,Z) when you drink. I don't want to be around you when you are drinking," or, "You communicated that you identify as an alcoholic. You have told me that you want to quit drinking and are not able to do it by yourself. Are you willing to try something different and would you like my help researching some of those options?" or, "While I feel glad to hear that you would like to quit drinking, I know I'm not the best person to help support you and know that I won't be able to support you as much as you may need. I am too personally invested in what you end up doing, and may force my ideas on you. Instead, I'm going to distance myself a bit so that I don't make decisions to control your behavior." or, "I feel fine with you drinking," or, "I don't want to be in a marriage with someone who identifies as alcoholic," or any number of "I statements" that may feel right for you.
12 step programs have been successful and are a good fit for a LOT of people. There are other options too. If he chooses to go to AA or if you choose to go to al-anon or ACOA (depending on how you identify), I suggest going to lots of different meetings. Try 'em on, and don't be afraid to keep on looking. Lot's of folks get a lot of relief from working the steps and getting a sponsor.
Good luck and big hugs.
PS, don't forget self care! Hot baths, tea, time away with your support system, good novels, journaling, exercise, rest/relaxation and the right kinds of food/liquids - just to name a few that help some people.