http://www.allaboutcounseling.com/codependency.htm

What is codependency? What's the definition?
There are many definitions used to talk about codependency today. The original concept of codependency was developed to acknowledge the responses and behaviors people develop from living with an alcoholic or substance abuser. A number of attributes can be developed as a result of those conditions.

However, over the years, codependency has expanded into a definition which describes a dysfunctional pattern of living and problem solving developed during childhood by family rules.

One of many definitions of codependency is: a set of *maladaptive, *compulsive behaviors learned by family members in order to survive in a family which is experiencing *great emotional pain and stress.

*maladaptive - inability for a person to develop behaviors which get needs met.

*compulsive - psychological state where a person acts against their own will or conscious desires in which to behave.

*sources of great emotional pain and stress - chemical dependency; chronic mental illness; chronic physical illness; physical abuse; sexual abuse; emotional abuse; divorce; hypercritical or non-loving environment.

As adults, codependent people have a greater tendency to get involved in relationships with people who are perhaps unreliable, emotionally unavailable, or needy. And the codependent person tries to provide and control everything within the relationship without addressing their own needs or desires; setting themselves up for continued unfulfillment.

Even when a codependent person encounters someone with healthy boundaries, the codependent person still operates in their own system; they’re not likely to get too involved with people who have healthy boundaries. This of course creates problems that continue to recycle; if codependent people can’t get involved with people who have healthy behaviors and coping skills, then the problems continue into each new relationship.