Emir (also sometimes rendered as Amir or Ameer) is a title of nobility historically used in Islamic nations of the Middle East and North Africa. Originally it was a title of honor given to descendants of Mohammed via his daughter Fatima Zahra. Centuries after the time of Mohammed it became used in a wider range of contexts, such as the title used by cheiftains of Bedouins of Arabia and by nobles and officials of the Ottoman Empire.
The word emir is also used less formally for leaders in certain contexts, for example the leader of a group of pilgrims to Mecca is called an emir hadji.
The Caliphs used the title emir al mumenin, "Commander of the Faithfull".
Emir is also the term used by the Kuwaiti al-Sabah dynasty to refer to their ruling monarch since their independence on June 19, 1961. Qatar likewise uses this title since 1971, and Bahrain did so from 1971 to 2002.
In Arabic, another meaning of the word "emir" is prince, specifically, the male descendant of a sovereign. It also could mean the word "crown prince". For example, before being crowned as King Abdullah of Jordan, the son of King Hussein was referred to as "Emir Abdullah".