noun
ball bomb
A spherical explosive device; the term is straightforward and used in military or historical contexts.
ボール爆弾は第二次世界大戦中に使用された。
Ball bombs were used during World War II.
Compound of ボール (bōru, 'ball') and 爆弾 (bakudan, 'bomb'). The exact historical derivation is uncertain, but the term likely arose as a descriptive name for spherical explosive devices.