The word jungle has a primary sense meaning 'land covered with dense growth of trees, tall vegetation, vines, typically in tropical regions, and inhabited by predatory animals.' This is what most people think of when the word jungle is used in isolation.
However, jungle can also refer to any place with a dense, tangled growth of trees and vegetation, as illustrated in the sentence, 'I need to take care of the jungle in my backyard.' This meaning is a secondary sense of jungle. It shares the semantic components 'plant life' and 'density' with the primary sense of jungle. It does not share the components 'tropical' and 'predatory animals.'