The names of the star in the sky come from a wide variety of sources and reflect the influence of many of the greatest cultures of human history. Many names are directly translated from Arabic or Greek.
Almagest is the latin name of an Arabic translation of the famous "Great Treatise" by Ptolemy who in turn based much of his work on the older work of Hipparchus. It reflects much of the ancient world's knowledge of astronomy and gives the names of many stars.
The science of astronomy today owes much to early Islamic astronomers. The reason astronomers today call Almagest by an Arabic name rather than by a Greek, Roman, or even Egyptian name dates back to the period in Europe known as the "Dark Ages" where much knowledge was lost or forgotten. During the renaissance, European astronomers depended heavily on the existing knowledge of astronomers from the Islamic world.