(äkhmäd' mērzä') , 1898–1930, shah of Persia (1909–25), son of Muhammad Ali. The last of the Qajar dynasty, he came to power as a result of a coup against his father. A regent initially ruled for him. A weak figure, Ahmad was overthrown in 1921 in a military coup by Reza Khan (later Reza Shah Pahlevi). The shah, unable to oppose the new government, left (1923) for Europe, where he died.