Alcoholism is a term with multiple and sometimes conflicting definitions. In common and historic usage, alcoholism refers to any condition that results in the continued consumption of alcoholic beverages despite the health problems and negative social consequences it causes. Medical definitions describe alcoholism as a disease which results in a persistent use of alcohol despite negative consequences. Alcoholism may also refer to a preoccupation with or compulsion toward the consumption of alcohol and/or an impaired ability to recognize the negative effects of excessive alcohol consumption. Although not all of these definitions specify current and on-going use of alcohol as a qualifier, some do, as well as remarking on the long-term effects of consistent, heavy alcohol use, including dependence and symptoms of withdrawal.

While the ingestion of alcohol is, by definition, necessary to develop alcoholism, the use of alcohol does not predict the development of alcoholism. The quantity, frequency and regularity of alcohol consumption required to develop alcoholism varies greatly from person to person. In addition, although the biological mechanisms underpinning alcoholism are uncertain, some risk factors, including social environment, emotional health and genetic predisposition, have been identified.

Most people think of the Alcoholics Anonymous when asked about the term 'alcoholism'. In fact it was first used as early as 1849 by a Swedish physician. In the U.S.A., 'alcoholism' was first brought into popular use by the birth of the AA in 1939. The 'Big Book' used by the AA lacked any clear definition, so it compared it to an illness like an allergy.

E. Morton Jellinek was a pioneer in perceiving alcoholism as a legitimate disease. His study in 1960 limited the definition of alcoholism to patients showing a genetic history of the disease. Modern medical definitions have been revised since then, but the majority of people in medicine still believe it is an illness, and not just a social choice. Dr. Peele and Dr. Fingarette are exceptions, stating that alcoholism is not a disease. They concede that the term 'alcoholism' refers to an illness, and refer instead to the term 'heavy drinking' when discussing excessive alcohol consumption.

Due to alcoholism's unclear definition, the disease is often hard to precisely detect. There is no physiological difference between someone who drinks frequently and an alcoholic. One must assess objectively the negative effects alcohol consumption is having on a person's life and the benefits the drinker believes to be receiving from continuing to abuse alcohol. It is often obvious when an alcoholic's life has been severely damaged by excessive drinking, but identifying the person as an alcoholic can be difficult in more complicated cases.

Alcoholism makes a person consume excessive amounts of alcohol that is dangerous for his health. The disease also can impact others by virtue of the alcoholic's behaviour which lacks judgement or restraint.

Alcoholics often drink even after the disease has a noticeable impact on their health. The disease often results in cirrhosis, increased risk of cancer, epilepsy, heart disease, pancreatitis and death in many instances.