Addiction, nowadays, describes the power, attraction, and danger of a host of things, from substances to behaviours, from foods to fashions. The extraordinary growth in its application indexes the medicalisation of everyday life. In 17th-century English, addiction meant the practice, originally described in Roman law, of handing over a human being to a master. It also referred to passing objects in the marketplace to the highest bidder. Alongside these meanings was the figurative use of giving oneself over to a habit or pursuit, such as reading, sport, or smoking tobacco. These meanings remained remarkably stable until very recently. The almost automatic assumption that the “addict” is trapped in dependency is a product of 20th-century medically-informed social and criminal policy. Research into the physiological effects of drugs and alcohol led to the linguistic displacement in medicine of “drunks” or “sots” with “chronic alcoholics” and “inebriates”, while addicts came to be construed as congenitally bereft of moral agency, unable to help themselves. In effect, this was the secularisation of “possession”. Crucially, the addict's possession was framed in terms of physical and (increasingly) psychological dependence. This physio-psychological view was readily extended to other behaviours, such as certain sexual proclivities and gambling. In the 4th edition of the American Diagnostic and Statistical Manual of Mental Disorders, addiction was replaced by “substance dependency”. Criminologists and social policy analysts solidified this understanding. So, too, inadvertently, did historians: seeking to comprehend and demystify “addiction history”, they helped cement its synonymous use with dependency. Thus, in recent history, most of addiction's moderate meanings, legal and civil, have been stripped away, replaced by medically verified and morally enforced models of extreme and hopeless dependence, requiring intervention, control, and cure. But contradictions abound: the demon alcohol, destroyer of social stability and family life, and the close companion of psychiatric and behavioural pathologies, is legally available. Other “substances”, once medically widely deployed, are criminalised and held to have no positive properties. And, within the wider culture, dependence on the products of the marketplace is encouraged at the same time as being demonised as seductive and addictive.