RUM can refer to:

• the Remington Ultra Magnum family of cartridges
• the US Military designation for a ship-launched, anti-submarine guided missile. Examples include the RUM-139 VL-ASROC
• Real-User Monitoring (RUM) is a term used in measuring internet web application performance.
• University of Puerto Rico at Mayagüez

Rum is a distilled alcoholic beverage made from sugarcane byproducts, such as molasses, or directly from sugarcane juice, by a process of fermentation and distillation. The distillate, a clear liquid, is then usually aged in oak barrels.

Rùm , a Scottish Gaelic name often anglicised to Rum, is one of the Small Isles of the Inner Hebrides, in the district of Lochaber, Scotland. For much of the 20th century the name became Rhum, a spelling invented by the former owner, Sir George Bullough, because he did not relish the idea of having the title "Laird of Rum".

Rûm (pronounced ), also transliterated as Roum or Rhum (in Koine Greek "Ρωμιοί" or "Romans", in Arabic  الرُّومُ ar-Rūm, Persian/Turkish  Rûm, from Middle Persian Rhōm), is a generic term used at different times in Muslim world to refer to:

• ethnocultural minorities such as the various Christian groups living in the Near East and their descendants, notably the Antiochian Greek Christians who are members of the Greek Orthodox Church of Antioch and the Melkite Greek Catholic Church of Syria, Lebanon, Northern Israel and the Hatay Province in Southern Turkey whose liturgy is still based on Koine Greek (called Al-Rûm)
• more generally, to non-Muslim subjects of the Ottoman Empire or citizens of Turkey (Rûmi or Rûm in the broader sense, but that use is disappearing from the quasi-extinction of Greek communities in Izmir, Istanbul, Cappadocia, and the Black Sea coast).
• geographic areas such as the Balkans and Anatolia generally to the Eastern Roman Empire in particular or to the Seljuk Sultanate of Rûm in Medieval Turkey.