Translation guide
A non-lethal explosive device that produces a blinding flash and deafening noise to temporarily disorient people.
The most common and widely understood term for a stun grenade in Japanese.
Literally 'flash bullet/shell'. This is the standard technical and military term for a stun grenade, emphasizing the blinding flash.
警察は突入前に閃光弾を投げ込んだ。
The police threw a stun grenade before storming in.
Direct loanword from English. Commonly used in games, movies, and casual contexts, but less formal than 閃光弾.
ゲームでスタングレネードを使った。
I used a stun grenade in the game.
Terms that highlight the temporary blinding and deafening effect rather than the device itself.
Literally 'flash sound shell'. A more technical term used in official documents or specifications, explicitly mentioning both flash and sound.
特殊部隊は閃光音響弾を使用して人質を救出した。
The special forces used a stun grenade to rescue the hostages.
In military or police contexts, 閃光弾 is standard. In video games or pop culture, スタングレネード is often used. 閃光音響弾 is very technical and rarely used in everyday conversation.