'fix' is a term used for a dose of something that is addictive. "He hasn't had his nicotine fix" means he hasn't had his 'dose' of nicotine yet. ie. He hasn't had a cigarette or piece of chewing tobacco, etc. Often the term 'fix' is used for substances or drinks that aren't that addictive, but we *think* we need. I can say, "I need my morning fix of coffee every day". I'm comparing my need for a 'fix' of coffee to a need for a 'dose of a drug'. I'm exaggerating that I need my coffee to create a little humour. Similarly, if you say "I haven't had my nicotine fix', it's possible you are just exaggerating and making a joke of that fact that you *need* a cigarette.

Fix- To repair, put together, or to make it right. As in with an addiction it Means to make it right. As in making the drug addict right or feeling normal by getting his/her fix. Addicts who do certain drugs have withdrawals wich causes them to feel sick and by having thier fix they are getting thier routine dose to make themselves feel right. ...1) I was really sick until I got my fix of heroin, and than it made me feel right or not sick anymore.