Alcohol abuse is the excessive use of alcohol products. This can be through chronic, daily use of alcohol to the point of drunkeness.
This type of drinking is essentially an addiction like any other abusable substance. There are people who drink heavily and daily, yet continue to function in society. These are sometimes referred to functional alcoholics while others are completely taken over by alcohol use and are unable to function. If a substance is interfering with employment, relationships (family, friends, or romantic), and health then it can be surmised that the substance is being abused.
Another form of alcohol abuse is "binge-drinking" where a person will periodically drink to excess with periods of sobriety in between times.