I am in danger of quoting every sentence in Gerald May's Addiction and Grace: Love and Spirituality in the Healing of Addictions.
Here, May defines "addiction."
"Addiction exists wherever persons are internally compelled to give energy to things that are not their true desires. To define it directly, addiction is a state of compulsion, obsession, or preoccupation that enslaves a person’s will and desire. Addiction sidetracks and eclipses the energy of our deepest, truest desire for love and goodness. We succumb because the energy of our desire becomes attached, nailed, to specific behaviors, objects, or people. Attachment, then, is the process that enslaves desire and creates the state of addiction." (P. 14)