The term 'FORTIFIED TOWER IN A CASTLE' can be summarized as a structure that is built to protect a castle from attack. It is usually made of stone or brick and is often tall and narrow, with thick walls and few windows. The purpose of the tower is to provide a safe place for the inhabitants of the castle to retreat to in times of danger. The term 'KEEP' is used to refer to this type of tower, which is derived from the Middle English word 'kype, ' meaning a fortified tower.