In its broadest sense, codependency can be defined as an addiction to people, behaviors, or things.
Codependency is the fallacy of trying to control interior feelings by controlling people, things, and events on the outside.
To the codependent, control or lack of it is central to every aspect of life.
The codependent may be addicted to another person. In this interpersonal codependency, the codependent has become so elaborately wound up in the other person that the sense of self - personal identity - is severely restricted, crowded out by that other person's identity and problems.
Additionally, codependents can be like vacuum cleaners gone wild, drawing to themselves not just another person, but also chemicals (alcohol or drugs, primarily) or things - money, food, sexuality, work. They struggle relentlessly to fill the great emotional vacuum within themselves.