This posting describes the newsgroup alt.smokers, including where to find more information. It should be read by anyone who wishes to post to the alt.smokers newsgroup. In the 1988 Surgeon General's Report, C. Everett Koop espoused a redefinition of addiction that would include tobacco. Likewise with sex.
Nicotine plays a part, but a small one.
That's why nicotine patches and chewing gum aren't very effective when it comes to quitting. Smoking is a way of life. While tobacco satisfies the first criteria, the second is more problematic in that not all smokers increase their usage. The third does not apply to tobacco since fever, vomiting, etc. By calling smoking an addiction, the definition has been changed to exclude the third criterion and weaken the second.