DIEST, a town and fortress of Belgium, in the province of Brabant, and the arrondissement of Löwen, is situated on the Demer, 28 miles E. by N. of Brussels. The manufactured are hats, leather, stockings, beer, and spirits. It was taken from the French by Marlborough in 1705 and recaptured the same year. The fortifications, which replace the old ramparts and walls, were commenced in 1837, and finished in 1853. The population in 1866 was 7561.