Aden, ah'den or a'den, a seaport town and territory on the southwest coast of Arabia, belonging to Great Britain. Occupying an important military position, Aden is strongly fortified and permanently garrisoned, and may be called the Gibraltar of the East. It is situated in the crater of an extinct volcano and is surrounded by rocky peaks, which attain a height of from 1000 to 1775 feet. The harbor is deep and commodious and Aden is one of the most important coaling stations on the route of vessels passing through the Suez Canal. The commerce is extensive and the town is the chief trading port on the coast of Arabia. Population in 1901, 43,974.