Cronin, A. J. (Archibald Joseph Cronin) (krō`nĭn), 1896–1981, Scottish novelist. He gave up his prosperous London medical practice to devote himself to writing after the success of his first novel, Hatter's Castle (1931). His novels, written in a direct simple style, reflect both his religious beliefs as a Roman Catholic and his medical training. He is best known for The Citadel (1937), The Keys of the Kingdom (1941), The Green Years (1944), Shannon's Way (1948), and Pocketful of Rye (1969).