A Zungenbecken, also called a tongue basin[1] or tongue-basin,[2] is part of a succession of ice age geological landforms, known as a glacial series. It is a hollow that is left behind by the ice mass, as the snout of the glacier (German: Gletscherzunge, lit. 'glacier tongue') recedes, which initially fills with meltwater, forming a proglacial lake, and later may be filled with surface water from streams or precipitation. When the glacier has more fully retreated this produces a finger lake or glacial piedmont lake (German: Zungenbeckensee, known as a Gletscherendsee of the glacial series in the Alpine Foreland). The term Zungenbecken is of German origin, but used in English language sources.[3][4][5]
Examples are the Tegernsee, Ammersee, Starnberger See, Lake Constance, Chiemsee, Tollensesee and the Baltic Sea.