an impassable dense forest (typically tropical)

The jungle is a place in a rain forest where the forest floor is crowded with plants. Like other rainy places, they have many rivers or streams. Scientists think that more types of animals and plants live in the jungles than everywhere else. When people talk about jungles, they sometimes mean the whole rainforest.

A Jungle

The crowding in a jungle leaves little room to walk. This may make it dangerous to people.