The term CASTLE SURROUND is composed of two words, MOAT and CASTLE. MOAT is a four-letter word which refers to a deep, wide ditch filled with water that surrounds a CASTLE, fort, or town, historically used as a defensive measure. CASTLE is a six-letter word which refers to a large fortified building or set of buildings, typically of the medieval period, surrounded by thick walls and protected by towers, battlements, and sometimes a MOAT. Together, CASTLE SURROUND refers to the defensive measures taken to protect a CASTLE, such as a MOAT, walls, and towers.