The Maghreb (Arabic: المغرب , Berber: Tamazɣa) is usually defined as much or most of the region of Northwest Africa, west of Egypt. The traditional definition as being the region including the Atlas Mountains and the coastal plains of Morocco, Algeria, Tunisia, and (usually) Libya, was later superseded, especially since the 1989 formation of the Arab Maghreb Union, by the inclusion of a fifth nation, Mauritania, and of the disputed territory of Western Sahara (mostly controlled by Morocco). During the Al-Andalus era in Spain, the Maghreb's inhabitants, Maghrebis, were known as "Moors"; the Muslim areas of Spain in those times were usually included in contemporary definitions of the Maghreb---hence the use of 'Moor' or 'Moors' to describe the Muslim inhabitants of Spain by Christian and other Western sources.

Historical terms for the region or various portions of it include Numidia, Libya, and Africa in classical antiquity. The term maghrib is in origin an Arabic word for "west, occident", denoting the westernmost territories that fell to the Islamic conquests of the 7th century. Today, it is used as a proper noun denoting the Maghreb, also known as المغرب العربي al-maghrib al-ʻarabīy "the Arab Maghreb" or المغرب الكبير al-maghrib al-kabīr "the great Maghreb" in Arabic. The definite form al-maghrib is used for the country of Morocco in particular. The Berber language alternative term for al-maghrib, Tamazgha, has been popularized by Berber activists since the last quarter of the 20th century.