noun
recoilless rifle; recoilless gun
A military term for a weapon that vents propellant gases to the rear to eliminate recoil. Used in technical or historical contexts.
自衛隊は無反動砲を装備している。
The Self-Defense Forces are equipped with recoilless rifles.
Compound of 無 (mu, 'without') + 反動 (handō, 'recoil') + 砲 (hō, 'gun/cannon'). A straightforward technical coinage.