A rectangular dolmen (German: Rechteckdolmen), extended dolmen (German: erweiteter Dolmen) or enlarged dolmen is a specific type of megalith, rectangular in shape, with upright sidestones and, usually, two capstones. The term rectangular dolmen was coined by Ekkehard Aner and is used especially in the German state of Schleswig-Holstein, where dolmens with this type of ground plan primarily occur. A more precise term, however, is extended dolmen, used by Ewald Schuldt and Ernst Sprockhoff, because these types of dolmen also occur with trapezoidal ground plans (e.g. the ).