1. marsh; swamp; wetland; bog; pond
ていうか、沼って掃除できるもんなの?I mean, can you actually clean a swamp?
2. obsession; addiction; being hooked on; getting sucked into
このゲームは一度始めたら沼だよ。Once you start this game, you'll be hooked.
3. ugly man
4. retard; mentally disabled person