noun
Katakana noun for a gun or firearm. 銃 is the more general Japanese word, while ガン often has an English-loanword feel and is common in names, compounds, games, and media contexts.
このゲームでは新しいガンを選べる。
In this game, you can choose a new gun.
映画の主人公は両手にガンを持っていた。
The movie's hero was holding guns in both hands.