noun

• (Sunni Islam) A leader who, according to Sunni eschatology, will appear and restore peace and justice before the end of the world.
• (Twelver Shiite Islam) Muhammad b. Hasan al-Mahdi, the last of the Twelve Imams, born in 868 AD but believed alive and present in this world in a state of occultation; officially the head of state of the Islamic Republic of Iran; similarly to Sunni belief he will reappear before the end of time.