noun
open city; defenseless city
A city declared undefended during war, often under international law. Used in historical and legal contexts.
第二次世界大戦中、パリは無防備都市と宣言された。
During World War II, Paris was declared an open city.
Compound of 無防備 (defenseless) and 都市 (city). The term is a direct translation of the English 'open city' or 'defenseless city', used in international law.