The Emirate of Transjordan (Arabic: , romanized: Imrat Sharq al-Urdun, lit.'Emirate of East Jordan'), officially known as the Amirate of Trans-Jordan, was a British protectorate established on 11 April 1921, which remained as such until achieving formal independence in 1946.

After the Ottoman defeat in World War I, the Transjordan region was administered within OETA East; after British withdrawal in 1919, this region gained de facto recognition as part of the Hashemite-ruled Arab Kingdom of Syria, administering an area broadly comprising the areas of the modern countries of Syria and Jordan. Transjordan became a no man's land following the July 1920 Battle of Maysalun, during which period the British in neighbouring Mandatory Palestine chose to avoid "any definite connection between it and Palestine". Abdullah entered the region in November 1920, moving to Amman on 2 March 1921; later in the month a conference was held with the British during which it was agreed that Abdullah bin Hussein would administer the territory under the auspices of the British Mandate for Palestine with a fully autonomous governing system.

The Hashemite dynasty ruled the protectorate, as well as the neighbouring Mandatory Iraq and, until 1925, the Kingdom of Hejaz to the south. On 25 May 1946, the emirate became the "Hashemite Kingdom of Transjordan", achieving full independence on 17 June 1946 when in accordance with the Treaty of London ratifications were exchanged in Amman. In 1949, it was constitutionally renamed the "Hashemite Kingdom of Jordan", commonly referred to as Jordan.

Emir (; Arabic: أمير ʾamīr [ʔaˈmiːr]), 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, Afghanistan, 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 (أميرة ʾamīrah), a cognate for princess. Prior to its use as a monarchical title, the term "emir" was historically used to denote a "commander", "general", or "leader" (for example, Amir al-Mu'min). In contemporary usage, "emir" is also sometimes used as either an honorary or formal title for the head of an Islamic, or Arab (regardless of religion) organisation or movement.