Longman Dictionary of Contemporary English - jungle

~ n 1 a thick tropical forest with many large plants growing very close together 2 a place that is very untidy and where a lot of things have been placed close together  (This place is turning into a jungle already.) 3 a situation in which it is difficult to become successful or get what you want, especially because a lot of people are competing with each other  (You've got to be tough - it's a jungle out there.)  (- see also concrete jungle, law of the jungle law (10))