There are a few "definitions" of alcoholism floating around, generally speaking a good rule of thumb just from my experience is "normal drinkers" don't wonder if they are alcoholics, as in if you are wondering if you have a problem with alcohol you usually do. Frequently in my experience "cross addiction" takes place as well, switching from Pot to Alcohol or vice versa, after a few years it gets bad enough to be quite obvious, but in the early stages of my alcoholism I smoked a lot of pot and drank less, as the years went by the pot disappeared as the liquor took over.
one is "If you are unable to quit for a year OR once you start drinking you can't always control the amount you drink (example if you go to have two drinks, ten times, and two of those times you end up drunk and didn't mean to)
A description I heard is If drinking alcohol makes you thirsty, as in after you have one you want another one, and the more you drink the thirstier you get and the more you want is a pretty good indication.
I would suggest reading this if you are interested
Big Book Online
Here is a pretty good description from it
AA Big Book - Chapter 3
There are also the Twenty questions from John Hopkins
20 Questions
Are You an Alcoholic? To answer this question, ask yourself the following questions and answer them as honestly as you can.
You do not ever have to show this to anyone, nor should you!
1. Do you lose time from work due to your drinking?
2. Is drinking making your home life unhappy?
3. Do you drink because you are shy with other people?
4. Is drinking affecting your reputation?
5. Have you ever felt remorse after drinking?
6. Have you gotten into financial difficulties as a result of your drinking?
7. Do you turn to lower companions and an inferior environment when drinking?
8. Does your drinking make you careless of your family's welfare?
9. Has your ambition decreased since drinking?
10. Do you crave a drink at a definite time daily?
11. Do you want a drink the next morning?
12. Does drinking cause you to have difficulty in sleeping?
13. Has your efficiency decreased since drinking?
14. Is drinking jeopardizing your job or business?
15. Do you drink to escape from worries or troubles?
16. Do you drink alone?
17. Have you ever had a complete loss of memory as a result of your drinking?
18. Has your physician ever treated you for drinking?
19. Do you drink to build up your self-confidence?
20. Have you ever been in a hospital or institution on account of drinking?
If you have answered YES to any one of the questions, there is a definite warning that you may be an alcoholic.
If you have answered YES to any two, the chances are that you are an alcoholic.
If you have answered YES to three or more, you are definitely an alcoholic.