language of the enemy; enemy language
Historical term used in Japan during WWII, especially for English. Now a historical reference; not used in modern everyday language.
戦時中、英語は敵性語として排斥された。
During the war, English was rejected as the language of the enemy.
Formed from 敵性 “enemy character; belonging to an enemy” and 語 “language.” It became a prominent wartime label for languages associated with enemy nations, especially English.