An emirate is a territory ruled by an emir, a title used by monarchs or high officeholders in the Muslim world. From a historical point of view, an emirate is a political-religious unit smaller than a caliphate. It can be considered equivalent to a principality in non-Muslim contexts.

Emir, sometimes transliterated amir, amier, or ameer, is a word of Arabic origin that can refer to a male monarch, aristocrat, holder of high-ranking military or political office, or other person possessing actual or ceremonial authority. The title has a long history of use in the Arab World, East Africa, West Africa, Central Asia, and the Indian subcontinent. In the modern era, when used as a formal monarchical title, it is roughly synonymous with "prince", applicable both to a son of a hereditary monarch, and to a reigning monarch of a sovereign principality, namely an emirate. The feminine form is emira, with the same meaning as "princess". Prior to its use as a monarchical title, the term "emir" was historically used to denote a "commander", "general", or "leader". In contemporary usage, "emir" is also sometimes used as either an honorary or formal title for the head of an Islamic, or Arab organisation or movement.