The Vietnamese word "cấm thành" can be translated into English as "forbidden citadel." It is a noun that refers to a fortified area or palace that is restricted or off-limits, often associated with historical contexts, such as royal palaces in Vietnam.
In academic or historical discussions, "cấm thành" can be used to analyze the significance of royal architecture in Vietnam, or in discussions about the socio-political implications of restricted areas in the imperial era.
While "cấm thành" specifically refers to a "forbidden citadel," the component "cấm" can imply prohibition or restriction in various contexts.