NEUSIEDL, LAKE OF (Hung. Fertő Tava), a lake of Hungary, extends between the counties of Edeburg and Weiselburg. It is about 23 miles in length and 7 in breadth, and varies from 9 to 13 feet in depth; area about 120 square miles. Its waters are not potable, from containing much sulphate of soda, with some muriate of soda and carbonate of soda. (See Bright's Travels in Hungary.) It is fed by the River Vulka. The principal towns on its shores are Rusht and Neusiedl.