JUDENBURG (the ancient Idunum), a town in the Austrian province of Styria, capital of a cognominal circle, on the Mur, 38 miles W. of Gratz. In the middle ages it carried on an important trade with Germany and Italy, but at present it has scarcely any trade, and its chief manufactures are gunpowder and ironware. On 7th April 1797, an armistice was signed here between the French and Austrians. Pop. about 2000.