An Arab ruler is a leader of an Arab nation or region. The term 'Arab ruler' can be used to refer to four different titles: Ameer (5 letters), EMIR (4 letters), Amir (4 letters), and Emeer (5 letters). Ameer and Emeer are the most commonly used terms, while EMIR and Amir are more specific titles that are typically used for rulers of smaller regions. All four titles refer to a leader who has authority over a certain area or population.