Kho·mei·ni (kō-mā'nē, KHō-, KHô'mā-nē') Iranian Shiite leader and head of state (1979-1989). Arrested (1963) and exiled (1964) for his opposition to Shah Muhammad Reza Pahlavi's regime, he returned to Iran on the shah's downfall (1979) and established a new constitution giving himself supreme powers. His reign was marked by a return to strict observance of the Islamic code.