Almagest (Arab, al, the, and Gr. greatest), a name given by the Arabians to Ptolemy's compend of astronomy, written at Alexandria in the 2d century, translated from Greek into Arabic in the 9th, and translated from Arabic into Latin in the 13th. A better Latin translation from the original Greek was published at Basel in 1541. The Greek text with a French translation was published at Paris in 4 vols. (1813-'28).