​LYCK, or Lyk, a town of Germany, in the Prussian province of East Prussia, 112 m. by rail S.E. of Königsberg, and close to the frontier of Poland, on a lake and river of the same name. Pop. (1900) 11,386. It is the chief town of the region known as Masuria. On an island in the lake is a castle formerly belonging to the Teutonic order, and dating from 1273, now used as a prison. There are iron-foundries, distilleries, breweries, tanneries, paper mills and flour mills, and a trade in grain and cattle.