No built-in space between the two (outer and inner) walls of the defensive circuit of cities and castles. Zwingers were built in the Middle Ages and early modern period to improve the defence of castles and town walls. The term is German and usually left untranslated. However, it is sometimes rendered as “outer courtyard” presumably referring to the subsequent role of a zwinger as a castle’s defences became redundant and it was converted into a palace or schloss, however, this belies its original purpose as a form of killing ground for the defence. The word is linked with zwingen, “to force”, perhaps because the Zwinger forced an enemy to negotiate it before assaulting the main defensive line.
