An addict, in the purest sense of the word, means: You cannot STOP. Faced with the temptation, you're going to give in. Though you may wrestle with it and hold it back for a day or a week or a month, it's always in the back of your mind AND IT'S ONLY A MATTER OF TIME UNTIL YOU FALL AGAIN. You act out, even though you know, intellectualy, that you shouldn't, and EVEN THOUGH YOU FEEL THAT YOU DON'T WANT TO.
You don't have to be living in the gutter to be an addict, and you don't have to be caught up with adultery and pr*stitutes. All you need is a little p*rn, and/or a little m*sturbation, every so often (you can even be an addict if all you look at is swimsuit magazines and circulars for women's apparel) AND YOU CAN'T STOP IT!
That's an addict.
BTW, if a person can't stop, it's also ONLY A MATTER OF TIME before the situation deteriorates. The addict in the gutter, how do you think he got there? Did he just one day decide he'd like to leave his wife and children and home and job and sleep under the stars? No. It started those 5 or 10 or 15 years earlier, when he found he couldn't live without his swimsuit magazine. And, chaval [what a pity!] he didn't think of himself as an addict THEN, and get the help he needed, and spare himself tons suffering.
Luckily, once we admit we have an addiction, there are many tools that can help us. See the GYE handbook for guidance. But the first step is to come to terms with the truth about ourselves.