1.
castle; fortress; castle compound
A fortified structure including its walls, moats, and surrounding defensive works. Often used to refer to the entire castle complex rather than just the main tower.
A more formal and comprehensive term than 城, emphasizing the entire fortified compound rather than just the main keep. Used in academic, historical, and tourism contexts. Japan's castles are major tourist attractions, and understanding 城郭 terminology enriches the experience of visiting them.