noun
dungeon; underground prison
Refers to a real-world underground prison or cell, often in a castle or fortress. Less common than the gaming sense in modern Japanese.
中世の城には地下にダンジョンがあった。
Medieval castles had dungeons underground.
noun
dungeon (in games); underground labyrinth
The dominant modern usage, referring to an underground maze or area in RPGs and video games where players explore, fight monsters, and find treasure.
このゲームのダンジョンはとても広くて、クリアするのに時間がかかる。
The dungeons in this game are very large and take a long time to clear.
次のダンジョンには強いモンスターがたくさんいるらしい。
I heard there are a lot of strong monsters in the next dungeon.