(the ancient Antunacum), a town in the Prussian province of the Lower Rhine and district of Coblenz, ten miles north-west of that town. It is situated on the Rhine, and was once strongly fortified, but its walls are now in ruins. It has tin and leather works; and exports mill-stones and pounded tufa, used as a cement, which hardens under water, and is much used by the Dutch in constructing their dikes. Pop. in 1849, 3785. Long. 7.4.E. Lat. 50. 57. N.