Khamr (Arabic: خمر) is an Arabic word for wine or intoxicant. In Islamic context, is variously defined as alcoholic beverages, wine or liquor. The "dominant belief" among Muslims is that consumption of alcohol in any form is forbidden, and in addition selling, transporting, serving, etc. alcohol is also a sin. However, according to Murtaza Haider of Dawn, "A consensus (ijma) on how to deal with alcohol has eluded Muslim jurists for more than a millennium".

How Khamr in Islam is defined varies by the school of jurisprudence (madhhab). Most Islamic jurists have traditionally viewed it as general term for any fermented intoxicating beverage, though one school (Hanafi) has limited it to alcohol derived from dates and grapes (whose consumption they also forbid). Over time, other intoxicants, such as opium and khat, have been classed by jurists as khamr. The punishment for consumption of alcohol is disagreed upon; some believe that any punishment for consuming alcohol is un-Islamic, while others believe it is flogging, though legal scholars disagree over whether the number of lashes should be 40 or 80.

Historically, many Muslim elites consumed alcohol, encompassing the reign of the Umayyads, the Abbasids, Islamic Spain (al-Andalus), and dynasties that ruled Egypt and the eastern, Persianate half of the Muslim world. Modern Islamic countries have low rates of alcohol consumption, and it is completely banned in several of them while strictly controlled in others (such as consumption being allowed only in private places or by non-Muslims). A minority of Muslims do drink and believe consuming alcohol is not Qur'anically forbidden. Muslim-majority countries produce a variety of regional distilled beverages such as arak (drink) and rakı. There is a long tradition of viniculture in the Middle East, particularly in Egypt (where it is legal) and in Iran (where it is banned).

In fiqh (Islamic jurisprudence), it refers to certain forbidden substances, and its technical definition depends on the madhhab (school of jurisprudence). Most jurists, including those from the Maliki, Shafiʽi, Hanbali and Ahl-i Hadith legal schools, have traditionally viewed it as general term for any intoxicating beverage made from grapes, dates, and similar substances. Hanafi jurists restricted the term to a narrower range of beverages. Over time, some jurists classified other intoxicants, such as opium and khat, as khamr, based on a hadith attributed to Muhammad stating,

Other traditions state: (Narrated Abu Kathir As-Suhaimi that he heard Abu Hurairah saying that Muhammad the Messenger of Allah said)

A minority of faqīh (experts in Islamic jurisprudence), particularly of the Hanafi school, take the concept of khamr literally and forbid only grape-based (or date-based) alcoholic beverages, allowing those made with other fruits, grains, or honey. Other sources (Shaykh Nabil Khan) speaking for the Hanafi Madhhab, state that while not all alcohol is khamr (alcohol not derived from dates and grapes is ‘non-khamr’), all alcohol consumption is forbidden if consumed 1) in sufficient quantity to intoxicate or if 2) consumed for recreational purposes, (i.e. medicinal use may be permitted).

Quranic verses that at least discourage alcohol include:

They ask you about wine (khamr) and gambling. Say, "In them is great sin and [yet, some] benefit for people. But their sin is greater than their benefit."