ALLIER, a department of France, on a river of the same name, which runs at the foot of a branch of the Cevennes Mountains. It extends over 2828 square miles, and in 1851 contained 336,758 inhabitants. It is composed of a part of the ancient province of Bourbonnois, and is divided into four arrondissements, viz., Mount Luçon, Moulins, Gannat, and La Palisse.