"improvement, alteration for the better," late 14c., "restoration;" mid-15c., "improvement," from Old French reformacion and directly from Latin reformationem (nominative reformatio), noun of action from past participle stem of reformare (see reform, v.). In reference to the European religious movement, it is attested by 1540s, borrowed from Luther. The movement began as a bid to reform doctrines and practices of the Church of Rome.