Jungle may refer to:
1. An area of tropical or sub-tropical rainforest
2. Or, by contrast, an area where the low-level vegetation is so dense as to make human movement difficult (the original meaning in various Indian languages/dialects)
3. An area where the prevalence of large predators or other aggressive animals makes vigilance necessary
4. By extension, an area of human activity where the lack of regulation or the nature of regulation makes constant vigilance necessary.
The law of the jungle is taken to mean "watch out for yourself" or "might is right". Kipling's poem "The Law of the Jungle" in The Second Jungle Book, though it sets out detailed rules, actually lists a set of behaviours in a pack of Indian wolves, intended to be interpreted in relation to human behaviour.