Foldyar, Or Duna-Foldvar (Foldvar-On-The-Danube), a town of Hungary, in the county of Tolna, on the right bank of the Danube, 47 m. S. of Buda; pop. in 1869, 12,382. It commands the communication between the upper and lower Danube, and is a depot for salt. The surrounding district is fertile, producing grains and wine; and the town has a considerable sturgeon fishery.