noun
former army; old military
Refers to a military force that existed in the past, especially in contrast to a current or post-war force. Often used in historical or political contexts.
旧軍の施設が今は博物館になっている。
A former military facility is now a museum.
noun
Imperial Japanese Army
Specifically denotes the army of Imperial Japan (pre-1945). Used in historical discussions about WWII and the pre-war period.
旧軍の資料を調べると、当時の作戦がよくわかる。
Studying Imperial Japanese Army documents reveals the strategies of that era.
Compound of 旧 (former, old) and 軍 (army, military). The term gained currency after WWII to refer to the disbanded Imperial Japanese military.