motte-and-bailey castle
noun [ C ] architecture specialized uk/ˌmɒt ən ˌbeɪ.li ˈkɑː.səl/ us/ˌmɑːt ən ˌbeɪ.li ˈkæs.əl/ (also motte and bailey)
城寨城堡
a type of castle in which there is a motte (= small hill) surrounded by a bailey (= open area) inside an outer wall