is a dependence on a behavior or substance that a person is
powerless to stop.
The term has been partially replaced by
the word dependence for substance abuse. Addiction
has been extended, however, to include mood-altering
behaviors or activities. Some researchers speak of two types
of addictions: substance addictions (for example,
alcoholism, drug abuse, and smoking); and process
addictions (for example, gambling, spending, shopping,
eating, and sexual activity). There is a growing recognition
that many addicts, such as polydrug abusers, are addicted to
more than one substance or process.